High titer recombinant AAV vector production in adherent and suspension cells

ABSTRACT

The present invention is directed to an in vitro method of producing a recombinant AAV virion in a mammalian host cell that comprises a functional adenoviral E1A gene and rAAV virions made by the method. Host cells are transfected with varying ratios of plasmids comprising the E1A gene and virions.

This application claims the benefit of U.S. Provisional Application No.61/872,523, filed on Aug. 30, 2013, which is hereby incorporated byreference in its entirety.

The instant application contains a Sequence Listing which has beensubmitted electronically in ASCII format and is hereby incorporated byreference in its entirety. Said ASCII copy, created on Aug. 28, 2014, isnamed A-1839-WO-PCT-SeqList082814_ST25.txt and is 2 kilobytes in size.

Throughout this application various publications are referenced withinparentheses or brackets. The disclosures of these publications in theirentireties are hereby incorporated by reference in this application inorder to more fully describe the state of the art to which thisinvention pertains.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to the field of recombinant viralvector production.

2. Discussion of the Related Art

Adeno-associated virus (AAV) systems have been used for gene delivery tomammalian cells. AAV is generally considered a good choice for genedelivery because it has not been associated with any human or animaldisease and does not appear to alter the biological properties of thehost cell upon integration. AAV, which belongs to the genusDependovirus, is a helper-dependent DNA parvovirus. Thus, in order foreffective AAV virion production to occur, the host cell must also beinfected with an unrelated helper virus, either adenovirus (Ad), aherpesvirus (HSV), or vaccinia virus. The helper virus suppliesaccessory functions that are necessary for most steps in AAVreplication. In the absence of such infection, AAV establishes a latentstate by insertion of its genome into a host cell chromosome. Subsequentinfection by a helper virus rescues the integrated copy which can thenreplicate to produce infectious viral progeny. AAV has a wide host rangeand is able to replicate in cells from any species so long as there isalso a successful infection of such cells with a suitable helper virus.For example, human AAV will replicate in canine cells co-infected with acanine adenovirus. For a review of AAV, see, e.g., Berns & Bohenzky,Advances in Virus Research 32:243-307 (Academic Press, Inc. 1987).

The AAV genome is composed of a linear single-stranded DNA moleculewhich contains 4681 bases (Berns & Bohenzky, supra). The genome includesinverted terminal repeats (ITRs) at each end which function in cis asorigins of DNA replication and as packaging signals for the virus. TheITRs are approximately 145 bp in length. Inverted terminal repeats flankthe unique coding nucleotide sequences for the non-structuralreplication (Rep) proteins and the structural (VP) proteins. The VPproteins (VP1, -2 and -3) form the capsid. The terminal 145 nucleotidesare self-complementary and are organized so that an energetically stableintramolecular duplex forming a T-shaped hairpin may be formed. Thesehairpin structures function as an origin for viral DNA replication,serving as primers for the cellular DNA polymerase complex.

The internal nonrepeated portion of the genome includes two large openreading frames, known as the AAV rep and cap regions, respectively.These regions code for the viral proteins involved in replication andpackaging of the virion. In particular, a family of at least four viralproteins are synthesized from the AAV rep region, Rep 78, Rep 68, Rep 52and Rep 40, named according to their apparent molecular weight.Following wild type AAV infection in mammalian cells the Rep genes (i.e.Rep78 and Rep52) are expressed from the P5 promoter and the P19promotor, respectively and both Rep proteins have a function in thereplication of the viral genome. A splicing event in the Rep ORF resultsin the expression of actually four Rep proteins (i.e. Rep78, Rep68,Rep52 and Rep40). However, it has been shown that the unspliced mRNA,encoding Rep78 and Rep52 proteins, in mammalian cells are sufficient forAAV vector production. Also in insect cells the Rep78 and Rep52 proteinssuffice for AAV vector production.

The AAV cap region encodes at least three proteins, VP1, VP2 and VP3.For a detailed description of the AAV genome, see, e.g., Muzyczka,Current Topics in Microbiol. and Immunol. 158:97-129 (1992). Fordescriptions of the construction of recombinant AAV virions see, e.g.,U.S. Pat. Nos. 5,173,414 and 5,139,941; International PublicationNumbers WO 92/01070 (published 23 Jan. 1992) and WO 93/03769 (published4 Mar. 1993); Lebkowski et al., Molec. Cell. Biol. 8:3988-3996 (1988);Vincent et al., Vaccines 90 (Cold Spring Harbor Laboratory Press 1990);Carter, Current Opinion in Biotechnology 3:533-539 (1992); Muzyczka,Current Topics in Microbiol. and Immunol. 158:97-129 (1992); Kotin,Human Gene Therapy 5:793-801 (1994).

It is possible to make a mammalian cell line stably expressing AAV repand AAV cap proteins, but it was also reported that AAV rep protein wastoxic to the cells. A majority of rAAV vector production is still doneby transient transfection. In addition, transient transfection offersthe ease of AAV serotype selection by changing DNA constructs comparedto the use of stably transfected cell lines.

Consequently, most ontemporary recombinant AAV (rAAV) virion productioninvolves co-transfection of a host cell with an AAV vector plasmidusually containing one or more transgenes flanked by AAV ITRs, and aconstruct which provides AAV helper functions (e.g., rep and cap) tocomplement functions missing from the AAV vector plasmid. In thismanner, the host cell is capable of expressing the AAV proteinsnecessary for AAV replication and packaging. To provide accessoryfunctions, the host cell is then be transfected with a plasmid havingaccessory function or infected with a helper virus, typically aninfectious adenovirus (e.g., type 2 or 5), or herpesvirus.

More particularly, AAV vector plasmids can be engineered to contain afunctionally relevant nucleotide sequence of interest (e.g., a selectedgene, antisense nucleic acid molecule, ribozyme, or the like) that isflanked by AAV ITRs which provide for AAV replication and packagingfunctions. After an AAV helper plasmid and an AAV vector plasmid bearingthe nucleotide sequence are introduced into the host cell by transienttransfection, the accessory function can be provided either bytransfecting the cells with a plasmid with accessory genes or byinfecting cells with a helper virus, most typically an adenovirus,which, among other functions, transactivates the AAV promoters presenton the helper plasmid that direct the transcription and translation ofAAV rep and cap regions. Upon subsequent culture of the host cells, rAAVvirions (harboring the nucleotide sequence of interest) and helper virusparticles are produced.

Adeno-associated virus (AAV) has a stable capsid that is composed of 60copies of three capsid proteins (VP1, 2 and 3). (Berns K, and Parrish CR, Parvoviridae. in Fields Virology, 5th ed. Ed. by David M. Knipe,Wolters Kluwer/Lippincott Williams & Wilkins, Philadelphia (2007). Thecommonly used recombinant AAV (“rAAV”) vector serotypes are AAV1-9, eachwith different tissue tropisms. (Zincarelli C, et al., Analysis of AAVserotypes 1-9 mediated gene expression and tropism in mice aftersystemic injection, Molecular Therapy 16:1073-1080 (2008)).

Recombinant AAV is one of the most promising viral gene transfer vectorsbecause it has high gene transfer efficiency, long-term gene expression,natural replication deficiency, and is non-pathogenic. (Coura R S andNardi N B., The state of the art of adeno-associated virus-based vectorsin gene therapy, Virology J. 4:99-105 (2007)). One of the majorchallenges for using rAAV vectors has been the difficulty in large scaleproduction of vectors for preclinical target identification/validationstudies, or use in large animal models and clinical trials of human genetherapy. (Allay, J A et al., Good manufacturing practice production ofself-complementary serotype 8 adeno-associated viral vector for ahemophilia B clinical trial, Hum Gene Ther. 2011; 22:595-604 (2011)).The principle of rAAV vector production is to supply three components tocultured cells: the gene of interest (“GOI”) expression cassette flankedby inverted terminal repeats (“ITR”s) of AAV, the rep and cap genes, andtrans-acting helper functions. Triple transfection of adherent HEK 293cells is a commonly used method for rAAV vector production (Xiao, X. andSamulski, R J., Production of high-titer recombinant adeno-associatedvirus vector in the absence of helper adenovirus, J. Virol. 72:2224-2232(1998)) and is reported to be efficient (Lock, M. et al, Rapid, simple,and versatile manufacturing of recombinant adeno-associated viralvectors at scale, Hum. Gene Ther. 21:1259-71 (2010)). However, cellculture work involved in rAAV production including expansion, seedingand transfection of adherent HEK 293 cells is cumbersome and resourceintensive. Therefore, using cells suspended in aqueous liquid medium(“suspension cells”) for rAAV vector production is desirable due to itsscalability and cost effectiveness.

Several systems using suspension cells to produce rAAV vectors have beendeveloped and described in the literature:

1. Insect cell (Sf9 or H5 cells)/baculovirus: This system involvesinfection of insect cells with two recombinant baculoviruses to providerep, cap and GOI flanked with ITR and has high production efficiency.(Urabe, M. et al., Insect cells as a factory to produce adeno-associatedvirus type 2 vectors, Hum. Gene Ther. 13:1925-1943 (2002)). Althoughinsect packaging cell lines were recently developed and the number ofrequired baculoviruses was reduced to one, this system still facesseveral drawbacks, such as long lead time and genomic instability of thebaculovirus. (Aslanidi, G. et al., An inducible system for highefficient production of recombinant production of recombinantadeno-associated virus (rAAV) vectors in insect Sf9 cells, Proc. NatlAcad. Sci. USA 106:5059-5064 (2009)).

2. HeLa based cell lines/Ad5 or HSV-1: This approach requires generatinga stable rAAV packaging cell line and providing helper functions andtransgene cassette using Ad5, or generating a producer cell line andproviding helper functions with Ad5 or HSV1. (Gao, G P et al.,High-titer adeno-associated viral vectors from a Rep/Cap cell line andhybrid shuttle virus, Hum. Gene Ther. 9:2353-62 (1998); Thorne, B A etal., Manufacturing recombinant adeno-associated viral vectors fromproducer cell clones, Hum. Gene Ther. 20:707-14 (2009); Toublanc, E. etal., Identification of a replication-defective herpes simplex virus forrecombinant adeno-associated virus type 2 (rAAV2) particle assemblyusing stable producer cell lines, J. Gene Med. 6:555-64 (2004)). Themethod is suitable for large scale production, but generating stablecell lines is cumbersome and lengthy.

3. BHK21 cells/HSV system: This system utilizes two rHSV-1 vectors todeliver cis and trans factors required for rAAV vector production andhas been used for large scale rAAV vector production. (Booth, M J etal., Transfection-free and scalable recombinant AAV vector productionusing HSV/AAV hybrids, Gene Ther. 11:829-37 (2004)). However, thelengthy time to produce the master viral banks, fragility andpathogenicity/immunogenicity of HSV make this method less favorable.

All of the above methods 1-3 need to ensure the elimination of the virusused from the final rAAV vector preparation.

4. Suspension adapted HEK 293 cells/triple transfection: This is atraditional triple transfection method for rAAV vector production, butin suspension-adapted cells instead of adherent cells. Advantages ofthis method are scalability, flexibility, simplicity and speed, whichare important when different combinations of serotypes and/or GOIs andstrict timelines are necessary.

Only a few protocols using suspension-adapted HEK 293 cells/tripletransfection have been reported and all were optimized using the onefactor at a time (OFAT) method. Park, et al. first explored thepossibility of combining suspension HEK 293 cells and polyethyleneimine(PEI) transfection for rAAV2 vector production. (Park, J Y et al.,Scalable production adeno-associated virus type 2 vectors via suspensiontransfection, Biotech. Bioeng. 94:416-430 (2006)). The authorsdemonstrated that a similar amount of rAAV2 could be generated insuspension cells as compared to adherent cells, and HEK 293T cells weremore efficient for rAAV vector production than HEK 293 cells. The celldensity (0.5×10⁶ cells/ml) and the plasmid ratio (1:1:1;pHelper:pTrans:pCis, an equimolar ratio) were not optimized in thestudy, but the total amount of DNA was optimized to 3 μg/ml. Inaddition, media changes before and after transfections were required inthis protocol.

A more comprehensive study by Durocher, et al. optimized the ratio ofthe three plasmids (1:1:1 in HEK293E cells), the cell density (0.5×10⁶cells/ml, tested densities: 0.5, 1.0 and 2.0×10⁶ cells/ml in HEK293Fcells), and harvest time (48 h, to obtain higher infectious virusparticles (“IVP”) in 293F cells), while the amount of DNA (1 μg/ml) andpolyethyleneimine (PEI):DNA (2:1) ratio were kept constant. (Durocher, Yet al., Scalable serum-free production of recombinant adeno-associatedvirus type 2 by transfection of 293 suspension cells, J. Virol. Methods.144:32-40 (2007)).

Hildinger, et al. described a more complicated method for rAAV2production in HEK293E cells. Several media were first tested for rAAV2and rAAV2/5 vectors production and a 1:1 mixture of RPMI and Ex-Cell wasfound to be the best production medium. The authors reported that 1×10⁶cells/ml and 1.25 μg/ml DNA were optimal among the tested conditions.(Hildinger, M et al., High-titer, serum-free production ofadeno-associated virus vectors by PEI-mediated plasmid transfection inmammalian suspension cells, Biotechnol. Lett. 29:1713-21 (2007)). Thestudy also demonstrated that increasing capsid protein expression andaddition of soy peptones the day after transfection increased rAAV2vector production yields by approximately 40% and 30%, respectively.This study also showed that higher IVP was obtained when rAAV vectorswere harvested 48 hours post-transfection. However, the described methodis quite complex, since cells need to be pelleted and re-suspended forsplitting, washed before transfection and complemented with an equalvolume of Ex-Cell medium 4 hours after transfection. These complexprocedures are difficult to apply to large scale production.

Feng, et al. also studied rAAV2 vector production in suspension HEK293cells with hypothermic treatment. (Feng, L et al., Improvement in thesuspension-culture production of recombinant adeno-associated virus-LacZin HEK-293 cells using PEI-DNA complexes in combination with hypothermictreatment, Biotechnol Appl Biochem. 50:121-32 (2008)). The cytotoxity ofPEI was first explored and the PEI concentration (30 μg/ml) for 80% cellviability was chosen. Based on this data and a gel retardation assay,optimized values for the PEI:DNA ratio (5:1), cell density (0.5×10⁶cells/ml), and total DNA (3 μg/ml) were obtained using OFAT-basedoptimization. The authors showed that transfection efficiency increasedafter transient hypothermic incubation at 4° C. which arrested cells inG2/M phase. However, the correlation between the increase intransfection efficiency induced by hypothermic treatment and higher rAAVvector production was not shown. It is noteworthy that all of theseoptimizations used traditional OFAT method for rAAV2 production andresulted in similar optimized values for cell density (0.5-1×10⁶cells/ml), and DNA ratio (1:1:1 or 2:1:1, pHelper:pTrans:pCis), althoughtotal DNA (1-3 μg/ml) and the PEI:DNA ratios are different between thesereports (2:1, 3:1 and 5:1).

The present invention provides a way to produce rAAV virions in culturedmammalian cells, both adherent cells and suspension cells, which isparticularly desirable because it can dramatically reduce the input ofresources required. These and other benefits the present inventionprovides.

SUMMARY OF THE INVENTION

The present invention is directed to an in vitro method of producing arecombinant AAV virion in a mammalian host cell (that comprises afunctional adenoviral E1A gene, e.g., a HEK 293 cell) and to a rAAV madeby the method. The method involves incubating the cell in a transfectionmedium. The transfection medium can comprise a protein hydrolysate, forexample tryptone N1 (TN1). Optionally, the transfection medium contains0-20 mM sodium butyrate. Included in the transfection medium are also(i) an accessory construct comprising a plasmid (pHelper) comprisingadenoviral E2, E4Orf6, and VAI RNA genes operably linked to an origin ofreplication element and one or more other regulatory sequences; (ii) anAAV helper construct comprising a plasmid (pTrans) comprising AAV repand AAV cap coding regions operably linked to one or more regulatorysequences; and (iii) a recombinant AAV vector comprising a plasmid(pCis), comprising AAV inverted terminal repeats flanking a heterologousgene of interest operably linked to one or more regulatory sequences. Inthe inventive method, the ratio of pHelper:pTrans:pCis is 1:1 to 5:0.009to 0.36 (weight:weight:weight), and preferably 1:1 to 5:0.30 to 0.36(weight:weight:weight). These plasmid ratios (pHelper:pTrans:pCis,weight:weight:weight) diverge from the widely used 2:1:1, 1:1:1 and3:1:1 plasmid ratios previously known in the art for production eitherwith cells adherent to a solid substrate or with mammalian cells, suchas HEK 293 cells, suspended in an aqueous liquid transfection medium.

One distinct advantage of the inventive method is that it can beemployed with adherent HEK 293 cells or HEK 293 cells suspended in anaqueous liquid transfection medium, with a beneficial significantreduction in the total amount of DNA input required compared topreviously known methods. Encompassed by the method of producing arecombinant AAV virion in a HEK 293 cell, as described above, areimproved parameter values that include higher cell density suspension(e.g., at a cell density of 2.1-3.0×10⁶ cells/mL, preferably 2.2-2.7×10⁶cells/mL, or more preferably 2.4-2.6×10⁶ cells/mL, or even morepreferably about 2.5×10⁶ cells/mL), and/or 1.5 mg/L total DNA, and/or apreferred plasmid ratio of 1:5:0.31 (pHelper:pTrans:pCis,weight:weight:weight). For example, by employing the inventive parametervalues, equivalent amounts of genomic copies (GC) of rAAV2/8 vectorswere produced in 1 L of suspension HEK293T cells as compared withadherent HEK293T cells in one 10-layer cell culture chamber (e.g.,CellSTACK® 6360 cm² cell culture chamber; Corning Life Sciences). Inaddition, the inventive method employed in cell suspension significantlyreduced the amount of total DNA, pHelper and pCis-GOI by 62.5%, 88.1%and 92.6%, respectively, compared to another protocol used for adherentHEK293T cells. Moreover, the newly defined plasmid ratio was notuniquely beneficial to suspension production and working examples hereinshow that the inventive method can also be applied to rAAV2/8 (or otherspecies of hybrid rAAV) vector production in adherent HEK293T cellsusing CaPO₄-mediated transfection. Among the benefits of the inventivemethod is that it employs substantially lesser amounts of total DNApHelper and pCis than previously reported methods and OFAT methods. Inaddition, we also showed that further reduction of the amount of pCiscan greatly benefit rAAV production yield, when yields of rAAV vectorproduction for a particular pCis-GOI are much lower than that of averageproduction yields.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A-F shows generic plasmid maps of pHelper (FIG. 1A), pTrans (inthis example for rAAV2/8 hybrid; FIG. 1B), and pCis (in this examplewith eGFP as the heterologous gene of interest [GOI]; FIG. 1C) plasmidsthat can be used in the optimization of rAAV vector production inaccordance with the invention. FIG. 1D shows a more particular exampleof a pHelper plasmid; FIG. 1E shows a more particular example of apTrans plasmid (in this example for rAAV2/8 hybrid); and FIG. 1F shows amore particular example of a pCis plasmid (in this example with eGFP asthe heterologous GOI).

FIG. 2A-B illustrates that optimized conditions for rAAV2/5 vectorproduction in suspension cells generated by a one-factor-at-a-time(OFAT) method did not result in efficient rAAV2/8 vector production. InFIG. 2A, Immunoblot analysis of viral capsid proteins in cell lysates.rAAV2/8 vectors carrying various GOIs were generated in either 1 L ofsuspension HEK293T cells (lanes 1, 3, and 5) using the OFAT-optimizedprotocol or in adherent HEK293T cells (lanes 2, 4, and 6) in 10-layercell stacks. FIG. 2B shows relative titers of rAAV2/8-eGFP from one cellstack of adherent cells or 1 L of suspension HEK293T cells using theOFAT-optimized protocol. Suspension, n=1; adherent, n=2.

FIG. 3A-C shows a comparison of rAAV vector production in suspension andadherent HEK 293T cells. FIG. 3A shows relative titers of rAAV2/8-eGFPvectors generated from one liter of suspension HEK293T cells using theDOE-improved protocol (Susp.; n=2) or from adherent HEK293T cells in onecell stack (Adhe; n=2). FIG. 3B shows a comparison of rAAV yields forvectors carrying various GOIs and produced in either 1 L suspensionHEK293T cells or adherent HEK293T cells in a 10-layer CellSTACK® cellculture chamber. FIG. 3C shows a comparison of the total amount of DNAand amounts of individual plasmid DNAs used for 1 L of suspensionHEK293T cells transfected according to the DOE-improved protocol or foradherent HEK293T cells transfected in one 10-layer CellSTACK® cellculture chamber using the CaPO₄-mediated protocol.

FIG. 4A-B shows that the plasmid ratio revealed by DOE in suspensioncells (1:5:0.31) also works effectively for adherent HEK293T cells. InFIG. 4A, adherent HEK293T cells in one cell stack were transfected bymeans of the CaPO₄ method using the total amount of DNA and plasmidratio (pHelper:pTrans:pCis) identified in the DOE optimization(1:5:0.31, left) or the standard reported DNA amount and ratio (2:1:1,right). rAAV2/8 vectors carrying different GOIs (n=6) were purified andthe relative titers per CellSTACK® cell culture chamber are shown. FIG.4B shows a comparison of the amount of total DNA, pHelper DNA, pTransDNA, and pCis DNA used for adherent HEK293T cells transfected witheither the 1:5:0.31 or 2:1:1 (pHelper:pTrans:pCis-GOI) plasmid ratio.

FIG. 5 shows a comparison of the amount of plasmid DNAs used for rAAVvector production in various protocols. “*” Durocher Y., et al. J. VirolMethods 144:32-40 (2007); “#” Hildinger, M., et al. Biotechnol Lett.29:1713-1721 (2007); “$” Xiao et al. J Virol. 72:2224-32 (1998); “&”Cell density is 2×10⁶/ml at transfection, diluted to 1×10⁶ at 4 hoursafter transfection; “%” Agilent Technologies Inc' (Cat 240071) and Xiaoet al.'s (Xiao et al. J Virol. 72:2224-32 (1998)) protocols wereconverted to cell stack [“CS”] scale based on surface area of the cellculture chamber (CellSTACK®-10: 6360 cm², 100 mm dish: 55 cm²; CorningLife Sciences, Lowell, Mass.).

FIG. 6A-B illustrates that the optimized protocol for rAAV2/8 vectorproduction identified by DOE can also be applied to production ofserotypes rAAV2/1, 2, 2/5 and 2/9 in suspension cells. Twentymilliliters of suspension HEK293T cells were transfected using eitherthe OFAT—(optimized for rAAV2/5 vector production) or DOE—(optimized forrAAV2/8 vector production) optimized protocols as described in Example 1herein (Materials and Methods) and Table 2. At 72 hourspost-transfection, the relative titers (FIG. 6A) and capsid proteins(FIG. 6B) in cell lysates were analyzed by bDNA assay and Immunoblot,respectively. The bars represent the average of duplicates.

FIG. 7A-B demonstrates production of rAAV2/8 and rAAV2 vectors usingplasmid ratios predicted to produce 90% or greater of the optimal yield.Predicted plasmid ratio ranges are from Table 3. rAAV vectors wereproduced in suspension cells, using the DOE-optimal plasmid ratio oralternative ratios predicted to produce 90% of optimal yield.rAAV2/8-eGFP (A) or rAAV2-eGFP (B) were produced in 20-ml cultures andpurified with AVBSepharose (GE Healthcare Life Sciences) from celllysates. GC/ml was determined by bDNA assay. The bars represent theaverage of duplicates.

FIG. 8A-C shows a comparison of customized rAAV plasmids (“AMG”) withcommercially available and published plasmids in rAAV2/8 and rAAV2production using the DOE optimized protocol. In all experiments, rAAV2or rAAV2/8 vectors were produced in 20-ml cultures, which were thenpurified with AVB Sepharose from cell lysates and the GC/ml wasdetermined by bDNA assay. FIG. 8A and FIG. 8B. rAAV2/8 (A) and rAAV2 (B)production using either AMG2/8 or a commercially obtained AgilentTechnologies Inc.'s (“AGL2/8”) plasmid set. To compare rAAV2/8production yields, the AAV2 cap gene in pAAV-RC (AGL) was replaced bythe AAV8 cap gene (AGL2/8). The GOI is LacZ for AGL and eGFP for AMG;FIG. 8C shows rAAV2-eGFP vector production using AMG or the publishedpTrans plasmids pXX2 and pACG2 (Xiao et al. J Virol. 72:2224-32 (1998)).All experiments were carried out using the DOE optimized protocol andwith Amgen's pHelper and pCis-eGFP plasmids (FIG. 1A and FIG. 1C). Thebars represent the average of duplicates.

FIG. 9A-B shows a comparison of rAAV2 and 2/8 vector production inHEK293-6E and HEK293T cells. The rAAVs were produced in 20-mlsuspensions of HEK293T or HEK293-6E cells using DOE-improved orOFAT-optimized protocols (Table 2). In FIG. 9A, the rAAV in the lysatewas titered by bDNA assay after purification with AVB Sepharose; FIG. 9Brepresents an immunoblot of capsid proteins in the lysate. The barsrepresent the average of duplicates.

FIG. 10A-B shows a comparison of rAAV vector production (rAAV2 in FIG.10A; rAAV2/8 in FIG. 10B) yields using the DOE and Durocher's protocols.Durocher's protocol (Table 4) was followed, except suspension HEK293Tcells and the pCis plasmid pAAV-LacZ were used and the cells wereharvested at 72 h post transfection. Also, TN1 and Na butyrate (“TB”)were added to one experimental group of Durocher's protocol to evaluatethe effects of TN1 and sodium butyrate on rAAV vector production usingDurocher's protocol. The bars represent the average of duplicates.

FIG. 11A-E illustrates optimization of TN1 and sodium butyrateconcentrations with DOE. In FIG. 11A, the DOE-optimization experimentswere carried out for rAAV2/8-eGFP production in suspension HEK293Tcells. Twenty four hours post transfection, TN1 and sodium butyrate(“But”) were added to the culture at the appropriate concentrations.Cells were harvested at 72 hours post-transfection, rAAV2/8-eGFP in celllysates from each 20-ml culture was purified with AVB Sepharose, andrelative titers were determined by bDNA assay; FIG. 11B shows theprediction profiles of effects of TN1 and sodium butyrate on rAAV2/8vector production. The average optimal concentration was also shown inFIG. 11A; FIG. 11C shows a comparison of the titer yields before andafter optimization of the additive concentrations. The rAAV2/8 vectorswere produced in 20-ml culture, and TN1 and sodium butyrate (“But”) wereadded 24 hours after transfection at concentrations indicated in thefigure. The rAAV2/8 vectors were purified from lysate and GC/ml wasdetermined by bDNA assay. Each bar represents the average of duplicates.The ranges of parameters for experimental design, optimal and 90% ofoptimal values, and typically used concentrations are shown in Table 5herein. FIG. 11D shows the comparison of AAV8-empty vector (rAAV2/8 doesnot carry GOI) production in small (20-mL) and large (1-L) scale. Theculture volumes were depicted at the top of the figure. 293T cells weretransfected in duplicate according to DOE-optimized condition.Immediately after transfection, 20 ml of culture were removed from the1-L transfection and cultured in a 125-ml flask (20 ml from 1 L).Different amount of TN1 and sodium butyrate were added to the culture 24h post transfection, as shown in the figure. The rAAV8-empty vector wasthen purified with AVB-Sepharose and the capsid proteins were analyzedwith silver stain (FIG. 11D), and titer for each sample was determinedby bDNA assay (FIG. 11E).

FIG. 12A shows an immunoblot analysis of AAV cap expression. HEK293Tcells (1 liter) were transfected with pHelper, pTrans and variouspCis-GOIs using the DOE-optimized method described in Example 2. Threedays after transfection, cells and conditioned medium were harvested.Harvested rAAV vectors were separated on 4-20% SDS-PAGE. AAV capsidproteins were detected by immunoblot with anti-VPs antibody (FitzgeraldIndustries International, Inc., Acton, Mass., cat. #10R-A114a).Molecular weight markers are indicated on the left and esxperessed GOIsare indicated on top of the gel.

FIG. 12B-C show that lowering the amount of pCis-Kcnj14 resulted inincreased AAV cap expression and greater yields of rAAV8-Kcnj14 vector.HEK293T cells (20 ml batch cultures) were transfected with fixedDOE-optimized amounts of pHelper, and pTrans, and various amounts ofpCis-Kcnj14 (1 to 1/256 of the DOE-optimized amount) using theDOE-optimized protocol described in Example 2. After 3 days, cells andmedium were harvested for analysis. FIG. 12B shows an immunoblotanalysis of AAV cap expression. AAV capsid proteins were detected by themethod described for FIG. 12A. Molecular weight markers are indicated onthe left and dilution factors are indicated on top of the gel. FIG. 12Cshows a quantification of rAAV8-Kcnj14 vector yields. The rAAV vectorsin the cells and conditioned medium were first purified by using AVBSepharose, and then the genome copies (GC) of the rAAV vectors weredetermined by the CyQant fluorescent method (Cell Biolabs, Inc.) anddata are presented as the fold-increase of GC (using the DOE-optimizedamount as 1). Dilution factors of pCis-Kcnj14 are indicated at thebottom.

FIG. 12D illustrates that decreasing the amount of pCis-Paqr9dramatically increased the production yield of rAAV-Paqr9 vector.HEK293T cells (1 liter batch culture) were transfected with fixedDOE-optimized amount of pHelper and pTrans, and various amounts ofpCis-GOIs (1, 1/32 and 1/64) using the DOE-optimized protocol describedin Example 2. Three days after transfection, cells and conditionedmedium were harvested. Harvested rAAV vectors were purified byAVB-Sepharose chromatography and the GC of purified rAAV were determinedby the CyQant fluorescent method (Cell Biolabs, Inc.). Dilution factorsof pCis-Paqr9 are indicated at the bottom.

FIG. 12E illustrates that decreasing the amount of pCis-Kcnj14dramatically increased the production yield of rAAV-Kcnj14. HEK293Tcells (1 liter batch culture) were transfected with fixed amounts ofDOE-optimized pHelper and pTrans, and various amounts of pCis-GOIs (1and 1/32) with the DOE-optimized method described in Example 2. Threedays after transfection, cells and conditioned medium were harvested.Harvested rAAV vectors were purified and quantified by the methoddescribed in FIG. 12D above. Dilution factors of pCis-Kcnj14 areindicated at the bottom.

DETAILED DESCRIPTION

The section headings used herein are for organizational purposes onlyand are not to be construed as limiting the subject matter described.

Definitions

Unless otherwise defined herein, scientific and technical terms used inconnection with the present application shall have the meanings that arecommonly understood by those of ordinary skill in the art. Further,unless otherwise required by context, singular terms shall includepluralities and plural terms shall include the singular. Thus, as usedin this specification and the appended claims, the singular forms “a”,“an” and “the” include plural referents unless the context clearlyindicates otherwise. For example, reference to “a protein” includes aplurality of proteins; reference to “a cell” includes populations of aplurality of cells.

The term “gene” is used broadly to refer to any nucleic acid associatedwith a biological function. Genes typically include coding sequencesand/or the regulatory sequences required for expression of such codingsequences. The term “gene” applies to a specific genomic or recombinantsequence, as well as to a cDNA or mRNA encoded by that sequence. A“fusion gene” contains a coding region that encodes a polypeptide oroligopeptide with portions from different proteins that are notnaturally found together, or not found naturally together in the samesequence as present in the encoded fusion protein (i.e., a chimericprotein). Genes also include non-expressed nucleic acid segments that,for example, form recognition sequences for other proteins.Non-expressed regulatory sequences including transcriptional controlelements to which regulatory proteins, such as transcription factors,bind, resulting in transcription of adjacent or nearby sequences.

“Gene transfer” or “gene delivery” refers to methods or systems forinserting foreign DNA into host cells. Gene transfer can result intransient expression of non-integrated transferred DNA, extrachromosomal replication and expression of transferred replicons (e.g.,episomes), or integration of transferred genetic material into thegenomic DNA of host cells. Gene transfer provides a unique approach forthe treatment of acquired and inherited diseases. A number of systemshave been developed for gene transfer into mammalian cells. See, e.g.,U.S. Pat. No. 5,399,346.

“Expression of a gene” or “expression of a nucleic acid” meanstranscription of DNA into RNA (optionally including modification of theRNA, e.g., splicing), translation of RNA into a polypeptide (possiblyincluding subsequent post-translational modification of thepolypeptide), or both transcription and translation, as indicated by thecontext.

As used herein the term “coding region” or “coding sequence” when usedin reference to a structural gene refers to the nucleotide sequenceswhich encode the amino acids found in the nascent polypeptide as aresult of translation of an mRNA molecule. A “coding sequence” or asequence that “encodes” a selected polypeptide, is a nucleic acidmolecule that is transcribed (in the case of DNA) and translated (in thecase of mRNA) into a polypeptide in vivo when placed under the controlof appropriate regulatory sequences. The boundaries of the codingsequence are determined by a start codon at the 5′ (amino) terminus anda transcriptional, or translational, as the case may be, stop codon atthe 3′ (carboxy) terminus.

The coding region is bounded, in eukaryotes, on the 5′ side by thenucleotide triplet “ATG” which encodes the initiator methionine and onthe 3′ side by one of the three triplets which specify stop codons(i.e., TAA, TAG, TGA).

By “recombinant virus” is meant a virus that has been geneticallyaltered, e.g., by the addition or insertion of a heterologous nucleicacid construct into the particle.

By “AAV virion” is meant a complete virus particle, such as a wild-type(wt) AAV virus particle (comprising a linear, single-stranded AAVnucleic acid genome associated with an AAV capsid protein coat). In thisregard, single-stranded AAV nucleic acid molecules of eithercomplementary sense, e.g., “sense” or “antisense” strands, can bepackaged into any one AAV virion and both strands are equallyinfectious.

A “recombinant AAV virion,” or “rAAV virion” is defined herein as aninfectious, replication-defective virus composed of an AAV proteinshell, encapsulating a heterologous nucleotide sequence of interest thatis flanked on both sides by AAV ITRs. A rAAV virion is produced in asuitable host cell, such as but not limited to a HEK 293 cell,comprising an AAV vector, AAV helper functions and accessory functions.In this manner, the host cell is rendered capable of encoding AAVpolypeptides that are required for packaging the AAV vector (containinga recombinant nucleotide sequence of interest) into infectiousrecombinant virion particles for subsequent gene delivery.

By “vector” is meant any genetic element, such as a plasmid, phage,transposon, cosmid, chromosome, virus, virion, etc., which is capable ofreplication when associated with the proper control elements and whichcan transfer gene sequences between cells. Thus, the term includescloning and expression vectors, as well as viral vectors.

The term “expression vector” or “expression construct” as used hereinrefers to a recombinant DNA molecule containing a desired codingsequence and appropriate nucleic acid control sequences necessary forthe expression of the operably linked coding sequence in a particularhost cell. An expression vector can include, but is not limited to,sequences that affect or control transcription, translation, and, ifintrons are present, affect RNA splicing of a coding region operablylinked thereto. Nucleic acid sequences necessary for expression inprokaryotes include a promoter, optionally an operator sequence, aribosome binding site and possibly other sequences. Eukaryotic cells areknown to utilize promoters, enhancers, and termination andpolyadenylation signals. A secretory signal peptide sequence can also,optionally, be encoded by the expression vector, operably linked to thecoding sequence of interest, so that the expressed polypeptide can besecreted by the recombinant host cell, for more facile isolation of thepolypeptide of interest from the cell, if desired. Such techniques arewell known in the art. (E.g., Goodey, Andrew R.; et al., Peptide and DNAsequences, U.S. Pat. No. 5,302,697; Weiner et al., Compositions andmethods for protein secretion, U.S. Pat. Nos. 6,022,952 and 6,335,178;Uemura et al., Protein expression vector and utilization thereof, U.S.Pat. No. 7,029,909; Ruben et al., 27 human secreted proteins, US2003/0104400 A1).

By an “AAV vector” is meant a vector derived from any adeno-associatedvirus serotype isolated from any animal species, including withoutlimitation, AAV-1, AAV-2, AAV-3, AAV-4, AAV-5, AAV-6, AAV-7, AAV-8 andAAV-9 serotypes, or hybrids of any of these. For example, hybrid AAVvectors are commonly made by employing hybrid trans-complementingconstructs that encode rep from AAV2, with cap derived from anotherserotype displaying the cell tropism of choice, e.g., AAV5.

In this example, the resulting rAAV virion is called rAAV2/5, in whichthe rep gene is based on recombinant AAV2, i.e., ITRs and rep from AAV2,while the capsid is based on AAV5. Typically, the cell or tissue-tropismdisplayed by such a hybrid rAAV virion will be the same as for the rAAVserotype that donated the cap, for example, the tropism of a rAAV2/5hybrid virus should be the same as that of AAV5.

AAV vectors can have one or more of the AAV wild-type genes deleted inwhole or part, preferably the rep and/or cap genes, but retainfunctional flanking ITR sequences. Functional ITR sequences arenecessary for the rescue, replication and packaging of the AAV virion.Thus, an AAV vector is defined herein to include at least thosesequences required in cis for replication and packaging (e.g.,functional ITRs) of the virus. The ITRs need not be the wild-typenucleotide sequences, and may be altered, e.g., by the insertion,deletion or substitution of nucleotides, so long as the sequencesprovide for functional rescue, replication and packaging.

A “recombinant AAV vector” or, interchangeably, “recombinant AAVconstruct” (rAAV vector) herein refers to a vector comprising one ormore heterologous polynucleotide sequences of interest, gene(s) ofinterest or “transgenes” that are flanked by AAV inverted terminalrepeat sequences (ITRs). Such rAAV vectors can be replicated andpackaged into infectious viral particles when present in a mammalian oran insect host cell that is expressing AAV rep and cap gene products(i.e. AAV Rep and Cap proteins). When a rAAV vector is incorporated intoa larger nucleic acid construct (e.g. in a chromosome or in anothervector such as a plasmid or baculovirus used for cloning ortransfection), then the rAAV vector is typically referred to as a“pro-vector” which can be “rescued” by replication and encapsidation inthe presence of AAV packaging functions and necessary helper functions.A recombinant AAV vector can be in the form of a plasmid (“pCis”),phage, transposon, cosmid, virus, or virion.

By “adeno-associated virus inverted terminal repeats” or “AAV ITRs” ismeant the art-recognized regions found at each end of the AAV genomewhich function together in cis as origins of DNA replication and aspackaging signals for the viral genome. AAV ITRs, together with the AAVrep coding region, provide for the efficient excision and rescue from,and integration of a nucleotide sequence interposed between two flankingITRs into a mammalian cell genome.

The nucleotide sequences of AAV ITR regions are known. See, e.g., Kotin,Human Gene Therapy 5:793-801 (1994); Berns, Parvoviridae and theirReplication, in Fundamental Virology (B. N. Fields and D. M. Knipe eds.,2d ed. 1991), for the AAV-2 sequence. As used herein, an “AAV ITR” neednot have the wild-type nucleotide sequence depicted in the previouslycited references, but may be altered, e.g., by the insertion, deletionor substitution of nucleotides. Additionally, the AAV ITR may be derivedfrom any of several AAV serotypes, including without limitation, AAV-1,AAV-2, AAV-3, AAV-4, AAV-5, AAV-7, AAV-8, AAV-9, etc. Furthermore, 5′and 3′ ITRs which flank a selected nucleotide sequence in an AAV vectorneed not necessarily be identical or derived from the same AAV serotypeor isolate, so long as they function as intended, i.e., to allow forexcision and rescue of the sequence of interest from a host cell genomeor vector, and to allow integration of the heterologous sequence intothe recipient cell genome when AAV Rep gene products are present in thecell.

By “AAV rep coding region” is meant the art-recognized region of the AAVgenome which encodes the replication proteins of the virus which arecollectively required to replicate the viral genome and to insert theviral genome into a host genome during latent infection, or functionalhomologues thereof such as the human herpesvirus 6 (HHV-6) rep genewhich is also known to mediate AAV-2 DNA replication. Thomson et al.,Virology 204:304-311 (1994). Thus, the rep coding region includes atleast the genes encoding for AAV Rep 78 and Rep 68 (the “long forms ofRep”), and Rep 52 and Rep 40 (the “short forms of Rep”), or functionalhomologues thereof. For a further description of the AAV rep codingregion, see e.g., Muzyczka, Current Topics in Microbiol. and Immunol.158:97-129 (1992); Kotin, Human Gene Therapy 5:793-801 (1994). The repcoding region, as used herein, can be derived from any viral serotype,such as the AAV serotypes described above. The region need not includeall of the wild-type genes but may be altered, e.g., by the insertion,deletion or substitution of nucleotides, so long as the rep genespresent provide for sufficient integration functions when expressed in asuitable recipient cell.

By “AAV cap coding region” is meant the art-recognized region of the AAVgenome which encodes the coat proteins of the virus which arecollectively required for packaging the viral genome. Thus, the capcoding region includes at least the genes encoding for the coat proteinsVP1, VP2 and VP3. For a further description of the cap coding region,see, e.g., Muzyczka, Current Topics in Microbiol. and Immunol.158:97-129 (1992); Kotin, Human Gene Therapy 5:793-801 (1994). The AAVcap coding region, as used herein, can be derived from any AAV serotype,as described above. The region need not include all of the wild-type capgenes but may be altered, e.g., by the insertion, deletion orsubstitution of nucleotides, so long as the genes provide for sufficientpackaging functions when present in a host cell along with an AAVvector.

“AAV helper functions” refer to AAV-derived coding sequences which canbe expressed to provide AAV gene products that, in turn, function intrans for productive AAV replication. Thus, AAV helper functions includethe rep and cap coding regions. The Rep expression products have beenshown to possess many functions, including, among others: recognition,binding and nicking of the AAV origin of DNA replication; DNA helicaseactivity; and modulation of transcription from AAV (or otherheterologous) promoters. The Cap expression products supply necessarypackaging functions. AAV helper functions are used herein to complementAAV functions in trans that are missing from AAV vectors.

The term “AAV helper construct” refer to a nucleic acid molecule thatincludes nucleotide sequences providing AAV helper functions deletedfrom an AAV vector which is to be used to produce a transducing vectorfor delivery of a nucleotide sequence of interest. AAV helper constructsare commonly used to provide transient expression of AAV rep and/or capgenes to complement missing AAV functions that are necessary for AAVreplication; however, helper constructs lack AAV ITRs and can neitherreplicate nor package themselves. AAV helper constructs can be in theform of a plasmid (“pTrans”), phage, transposon, cosmid, virus, orvirion. A number of AAV helper constructs have been described, such asthe commonly used plasmids pAAV/Ad and pIM29+45 which encode both Repand Cap expression products. See, e.g., Samulski et al., J. Virol.63:3822-3828 (1989); McCarty et al., J. Virol. 65:2936-2945 (1991). Anumber of other vectors have described which encode Rep and/or Capexpression products. See, e.g., U.S. Pat. No. 5,139,941.

The term “accessory functions” refers to non-AAV derived viral and/orcellular functions upon which AAV is dependent for its replication.Thus, the term encompasses proteins and RNAs that are required in AAVreplication, including those moieties involved in activation of AAV genetranscription, stage specific AAV mRNA splicing, AAV DNA replication,synthesis of Cap expression products and AAV capsid assembly.Viral-based accessory functions can be derived from any of the knownhelper viruses such as adenovirus, herpesvirus and vaccinia virus. Anaccessory function vector can be transfected into a suitable host cell,wherein the vector is then capable of supporting AAV virion productionin the host cell. Expressly excluded from the term are infectious viralparticles as they exist in nature, such as adenovirus, herpesvirus orvaccinia virus particles.

For example, adenovirus-derived accessory functions have been widelystudied, and a number or adenovirus genes involved in accessoryfunctions have been identified and partially characterized. See, e.g.,Carter, Adeno-Associated Virus Helper Functions, in I CRC Handbook ofParvoviruses (P. Tijssen ed., 1990); Muzyczka, Curr. Topics. Microbioland Immun 158:97-129 (1992). Specifically, early adenoviral gene regionsE1A (present, for example, in HEK 293 cells), E2A, E4Orf6, VAI RNA, andoptionally VAII RNA, and, optionally, E1B (also present in HEK 293cells) are thought to participate in the accessory process. Janik etal., Proc. Natl. Acad. Sci. USA 78:1925-1929 (1981). Herpesvirus-derivedaccessory functions have been described. See, e.g., Young et al., Prog.Med. Virol. 25:113 (1979). Vaccinia virus-derived accessory functionshave also been described. See, e.g., Carter (1990), supra; Schlehofer etal., Virology 152:110-117 (1986).

It has been demonstrated that the full-complement of adenovirus genesare not required for accessory functions. In particular, adenovirusmutants incapable of DNA replication and late gene synthesis have beenshown to be permissive for AAV replication. Ito et al., J. Gen. Virol.9:243 (1970); Ishibashi et al, Virology 45:317 (1971). Similarly,mutants within the E2B and E3 regions have been shown to support AAVreplication, indicating that the E2B and E3 regions are probably notinvolved in providing accessory functions. Carter et al., Virology126:505 (1983). However, adenoviruses defective in the E1 region, orhaving a deleted E4 region, are unable to support AAV replication. Thus,E1A and E4 regions are likely required for AAV replication, eitherdirectly or indirectly. Laughlin et al., J. Virol 41:868 (1982); Janiket al., Proc. Natl. Acad. Sci. USA 78:1925 (1981); Carter et al.,Virology 126:505 (1983). Other characterized Ad mutants include: E1B(Laughlin et al. (1982), supra; Janik et al. (1981), supra; Ostrove etal., Virology 104:502) (1980); E2A (Handa et al., J. Gen. Virol. 29:239(1975); Strauss et al., J. Virol. 17:140 (1976); Myers et al., J. Virol.35:665 (1980); Jay et al., Proc. Natl. Acad. Sci. USA 78:2927 (1981);Myers et al., J. Biol. Chem. 256:567 (1981)); E2B (Carter,Adeno-Associated Virus Helper Functions, in I CRC Handbook ofParvoviruses (P. Tijssen ed., 1990)); E3 (Carter et al. (1983), supra);and E4 (Carter et al. (1983), supra; Carter (1995)). Although studies ofthe accessory functions provided by adenoviruses having mutations in theE1B coding region have produced conflicting results, Samulski et al., J.Virol. 62:206-210 (1988), recently reported that E1B55k is required forAAV virion production, while E1B19k is not. In addition, InternationalPublication WO 97/17458 and Matshushita et al., Gene Therapy 5:938-945(1998), describe accessory function vectors encoding various Ad genes.Particularly preferred accessory function vectors comprise an adenovirusVA RNA coding region, an adenovirus E4 ORF6 coding region, an adenovirusE2A 72 kD coding region, an adenovirus E1A coding region, and anadenovirus E1B region lacking an intact E1B55k coding region. Suchvectors are described in International Publication No. WO 01/83797. Theterm “accessory construct” or, interchangeably, “accessory functionvector,” refers to a nucleic acid molecule that includes nucleotidesequences providing accessory functions. An accessory construct can bein the form of a plasmid (“pHelper”), phage, transposon, cosmid, virus,or virion.

By “capable of supporting efficient rAAV virion production” is meant theability of an accessory function vector or system to provide accessoryfunctions that are sufficient to complement rAAV virion productions in aparticular host cell at a level substantially equivalent to or greaterthan that which could be obtained upon infection of the host cell withan adenovirus helper virus. Thus, the ability of an accessory functionvector or system to support efficient rAAV virion production can bedetermined by comparing rAAV virion titers obtained using the accessoryvector or system with titers obtained using infection with an infectiousadenovirus. More particularly, an accessory function vector or systemsupports efficient rAAV virion production substantially equivalent to,or greater than, that obtained using an infectious adenovirus when theamount of virions obtained from an equivalent number of host cells isnot more than about 200 fold less than the amount obtained usingadenovirus infection, more preferably not more than about 100 fold less,and most preferable equal to, or greater than, the amount obtained usingadenovirus infection.

“AAV helper functions” refer to AAV-derived coding sequences which canbe expressed to provide AAV gene products that, in turn, function intrans for productive AAV replication. Thus, AAV helper functions includeboth of the major AAV open reading frames (ORFs), rep and cap. The Repexpression products have been shown to possess many functions,including, among others: recognition, binding and nicking of the AAVorigin of DNA replication; DNA helicase activity; and modulation oftranscription from AAV (or other heterologous) promoters. The Capexpression products supply necessary packaging functions. AAV helperfunctions are used herein to complement AAV functions in trans that aremissing from AAV vectors.

The term “AAV helper construct” refers generally to a nucleic acidmolecule that includes nucleotide sequences providing AAV functionsdeleted from an AAV vector which is to be used to produce a transducingvector for delivery of a nucleotide sequence of interest. AAV helperconstructs are commonly used to provide transient expression of AAV repand/or cap genes to complement missing AAV functions that are necessaryfor lytic AAV replication; however, helper constructs lack AAV ITRs andcan neither replicate nor package themselves. AAV helper constructs canbe in the form of a plasmid, phage, transposon, cosmid, virus, orvirion. A number of AAV helper constructs and vectors that encode Repand/or Cap expression products have been described. See, e.g., U.S. Pat.Nos. 6,001,650, 5,139,941, 6,376,237, 8,007,780, all incorporated hereinby reference in their entireties; Samulski et al. J. Virol. 63:3822-3828(1989); and McCarty et al. J. Virol. 65:2936-2945 (1991).

“Mammal” refers to any animal classified as a mammal, including humans,domestic and farm animals, and zoo, sports, or pet animals, such asdogs, horses, cats, cows, rodents (e.g., rats, mice, guinea pigs,hamsters), rabbits, pigs, sheep, goats, primates (e.g., monkeys, apes),etc. A “non-human” mammal is a mammal other than a human. The term“progeny” refers to any and all future generations derived anddescending from a particular cell or mammal.

“Non-human primate” or “NHP” means any non-human member of the orderPrimates, which contains prosimians (including lemurs, lorises, galagosand tarsiers) and, preferably simians (monkeys and apes), for example,baboons (Papio spp.), African green monkeys (Chlorocebus spp.), macaques(e.g., rhesus monkeys (Macaca mulatta), cynomolgus monkeys (Macacafascicularis)), spider monkeys (Ateles spp.), chimpanzees and bonobos(Pan spp.), gorillas (Gorilla spp.), gibbons (Hylobatidae), andorangutans (Pongo spp.). As noted, cynomolgus monkeys (also known as“cynos”, in singular “cyno”) are macaques (Macaca fascicularis synonymM. cynomolgus).

The term “transfection” is used to refer to the uptake of foreign orheterologous DNA by a cell, and a cell has been “transfected” whenexogenous DNA has been introduced inside the cell membrane. A number oftransfection techniques are generally known in the art. See, e.g.,Graham et al. (1973) Virology, 52: 456, Sambrook et al. (1989) MolecularCloning, a laboratory manual, Cold Spring Harbor Laboratories, New York,Davis et al. (1986) Basic Methods in Molecular Biology, Elsevier, andChu et al. (1981) Gene 13:197. Such techniques can be used to introduceone or more exogenous DNA moieties, such as a nucleotide integrationvector and other nucleic acid molecules, into suitable host cells. Cellsto be transfected are surrounded by an aqueous “transfection medium”suitable for the transfection method employed. In some cases, thetransfection medium can be a culture medium. The transfection medium cancontain about 0.1-2% (w/v) protein hydrolysate, or yeastolate, such asbut not limited to a peptone (e.g., tryptone [TN1]). (See, e.g., Pham etal., Transient gene expression in HEK293 cells: peptone additionpost-transfection improves recombinant protein synthesis, Biotechnol. &Bioeng. 90(3):332-44 (2005)). Within the inventive method, it can beuseful in small-scale transfection cultures (e.g., 20-mL), to includetryptone N1 (TN1) in the transfection medium at a concentration of1.4-1.6% (w/v), and preferably 1.475-1.525% (w/v), and more preferably1.50% (w/v)), and sodium butyrate can be added, optionally, at aconcentration of 0-20 mM. However, in large scale (e.g., 1-L) batches,0.5% (w/v) protein hydrolysate and 5 mM sodium butyrate increased yieldof rAAV virions.

The term “transformation” refers to a change in a cell's geneticcharacteristics, and a cell has been transformed when it has beenmodified to contain new DNA or RNA. For example, a cell is transformedwhere it is genetically modified from its native state by introducingnew genetic material via transfection, transduction, or othertechniques. Following transfection or transduction, the transforming DNAmay recombine with that of the cell by physically integrating into achromosome of the cell, or may be maintained transiently as an episomalelement without being replicated, or may replicate independently as aplasmid. A cell is considered to have been “stably transformed” when thetransforming DNA is replicated with the division of the cell.

“Homology” refers to the percent identity between two polynucleotide ortwo polypeptide moieties. Two DNA, or two polypeptide sequences are“substantially homologous” to each other when the sequences exhibit atleast about 50%, preferably at least about 75%, more preferably at leastabout 80%-85%, preferably at least about 90%, and most preferably atleast about 95%-98% sequence identity over a defined length of themolecules. As used herein, substantially homologous also refers tosequences showing complete identity to the specified DNA or polypeptidesequence.

In general, “identity” refers to an exact nucleotide-to-nucleotide oramino acid-to-amino acid correspondence of two polynucleotides orpolypeptide sequences, respectively. Percent identity can be determinedby a direct comparison of the sequence information between two moleculesby aligning the sequences, counting the exact number of matches betweenthe two aligned sequences, dividing by the length of the shortersequence, and multiplying the result by 100. Readily available computerprograms can be used to aid in the analysis, such as ALIGN, Dayhoff, M.O. in Atlas of Protein Sequence and Structure M. O. Dayhoff ed., 5Suppl. 3:353-358, National Biomedical Research Foundation, Washington,D.C., which adapts the local homology algorithm of Smith and WatermanAdvances in Appl. Math. 2:482-489, 1981 for peptide analysis. Programsfor determining nucleotide sequence identity are available in theWisconsin Sequence Analysis Package, Version 8 (available from GeneticsComputer Group, Madison, Wis.) for example, the BESTFIT, FASTA and GAPprograms, which also rely on the Smith and Waterman algorithm. Theseprograms are readily utilized with the default parameters recommended bythe manufacturer and described in the Wisconsin Sequence AnalysisPackage referred to above. For example, percent identity of a particularnucleotide sequence to a reference sequence can be determined using thehomology algorithm of Smith and Waterman with a default scoring tableand a gap penalty of six nucleotide positions.

Another method of establishing percent identity in the context of thepresent invention is to use the MPSRCH package of programs copyrightedby the University of Edinburgh, developed by John F. Collins and ShaneS. Sturrok, and distributed by IntelliGenetics, Inc. (Mountain View,Calif.). From this suite of packages the Smith-Waterman algorithm can beemployed where default parameters are used for the scoring table (forexample, gap open penalty of 12, gap extension penalty of one, and a gapof six). From the data generated the “Match” value reflects “sequenceidentity.” Other suitable programs for calculating the percent identityor similarity between sequences are generally known in the art, forexample, another alignment program is BLAST, used with defaultparameters. For example, BLASTN and BLASTP can be used using thefollowing default parameters: genetic code=standard; filter=none;strand=both; cutoff=60; expect=10; Matrix=BLOSUM62; Descriptions=50sequences; sort by=HIGH SCORE; Databases=non-redundant,GenBank+EMBL+DDBJ+PDB+GenBank CDS translations+Swissprotein+Spupdate+PIR. Details of these programs are well known in theart.

Alternatively, homology can be determined by hybridization ofpolynucleotides under conditions that form stable duplexes betweenhomologous regions, followed by digestion with single-stranded-specificnuclease(s), and size determination of the digested fragments. DNAsequences that are substantially homologous can be identified in aSouthern hybridization experiment under, for example, stringentconditions, as defined for that particular system. Defining appropriatehybridization conditions is within the skill of the art. See, e.g.,Sambrook et al., supra; DNA Cloning, supra; Nucleic Acid Hybridization,supra.

By the term “degenerate variant” is intended a polynucleotide containingchanges in the nucleic acid sequence thereof, that encodes a polypeptidehaving the same amino acid sequence as the polypeptide encoded by thepolynucleotide from which the degenerate variant is derived.

The term “heterologous” as it relates to nucleic acid sequences such ascoding sequences and control sequences, denotes sequences that are notin nature normally joined together, and/or are not normally associatedwith a particular cell. Thus, a “heterologous” region of a nucleic acidconstruct or a vector is a segment of nucleic acid within or attached toanother nucleic acid molecule that is not found in association with theother molecule in nature. For example, a heterologous region of anucleic acid construct could include a coding sequence flanked bysequences not found in association with the coding sequence in nature.Another example of a heterologous coding sequence is a construct wherethe coding sequence itself is not found in nature (e.g., syntheticsequences having codons different from the native gene). Similarly, acell transformed with a construct that is not normally present in thecell would be considered heterologous for purposes of this invention.Allelic variation or naturally occurring mutational events do not giverise to heterologous DNA, as used herein.

A “heterologous gene of interest” (GOI), or interchangeably “transgene”or interchangeably “heterologous nucleic acid” (HNA), is any desiredgene that can be incorporated into a rAVV virion, which has a packagingcapacity of about 5.3 kb (Joshua et al., J. Virol., 79: 9933-9944,2005), publication described that genome 5.3 kb and higher showedinefficient packaging efficiency, within a log). The transgeneoptionally may be operably linked to other genetic elements (such as apromoter, poly A sequence and the like) that may serve to modulate,either directly, or indirectly in conjunction with the cellularmachinery, the transcription and/or expression of the transgene.Alternatively or additionally, the transgene may be linked to nucleotidesequences that aid in integration of the transgene into the chromosomalDNA of the mammalian cell nucleus (as for example, in homologousrecombination). The transgene may be comprised of a nucleotide sequencethat is either homologous or heterologous to a particular nucleotidesequence in the mammal's endogenous genetic material, or is a hybridsequence (i.e. one or more portions of the transgene are homologous, andone or more portions are heterologous to the mammal's genetic material).The transgene nucleotide sequence may encode a polypeptide or a variantof a polypeptide, found endogenously in the mammalian host cell, it mayencode a polypeptide not naturally occurring in the mammalian cell (i.e.an exogenous polypeptide), or it may encode a hybrid of endogenous andexogenous polypeptides. Where the transgene is operably linked to apromoter, the promoter may be homologous or heterologous to themammalian cell and/or to the transgene. Alternatively, the promoter maybe a hybrid of endogenous and exogenous promoter elements (enhancers,silencers, suppressors, and the like).

For example, the GOI or transgene can be a readily detectable and/orassayable marker gene, such as a fluorescent protein gene (e.g., greenfluorescent protein (GFP) gene, phycobiliprotein gene), luciferase gene,or antibody resistance gene, which can be incorporated into theexpression construct whose expression or presence in the genome caneasily be detected. The marker gene is usually operably linked to itsown promoter or to another strong promoter from any source that will beactive or can easily be activated in the cell into which it is inserted;however, the marker gene need not have its own promoter attached as itmay be transcribed using the promoter of the gene of interest to beexpressed (or suppressed, in the case of a knock-out construct carryinga shRNA expression cassette). In addition, the marker gene will normallyhave a polyA sequence attached to the 3′ end of the gene; this sequenceserves to terminate transcription of the gene. Preferred marker genesare luciferase, beta-gal (beta-galactosidase), an alkaline phophatase(e.g., human placental secreted alkaline phosphatase [SEAP]), or anyantibiotic resistance gene such as neo (the neomycin resistance gene).The term “knockout construct” refers to a nucleic acid sequence that isdesigned to decrease or suppress expression of a protein encoded byendogenous DNA sequences in a cell (Khan et al., Nat Protoc. 6:482-501(2011) and Miller D G., Methods Mol Biol. 807:301-15 (2011)). Thenucleic acid sequence used as the knockout construct is typicallycomprised of (1) DNA from some portion of the gene (exon sequence,intron sequence, and/or promoter sequence) to be suppressed and (2) amarker sequence used to detect the presence of the knockout construct inthe cell. The knockout construct is inserted into a cell, and integrateswith the genomic DNA of the cell in such a position so as to prevent orinterrupt transcription of the native DNA sequence. Such insertionusually occurs by homologous recombination (i.e., regions of theknockout construct that are homologous to endogenous DNA sequenceshybridize to each other when the knockout construct is inserted into thecell and recombine so that the knockout construct is incorporated intothe corresponding position of the endogenous DNA). The knockout can alsobe achieved through highly conserved cellular phenomenon RNAinterference (RNAi)—the sequence-specific post-transcriptional silencingof gene expression mediated by small double-stranded RNAs (Grimm et al.,Hematology Am Soc Hematol Educ Program. 2007:473-81, Nizzardo et al.,Cell Mol Life Sci. 69:1641-50, 2012, and Miyazaki et al., Nat Med.18:1136-41. 2012). The knockout construct is typically composed of (1)RNA polymerase III [pol III] promoter, typically H1 or U6 promoters, todrive transcription of small RNA, (2) a nucleic acid sequence to encodesmall hairpin RNA ([shRNA], form a double-stranded RNA via hairpin) and(3) a transcription termination signal for RNA pol III. The knockoutconstruct is inserted into a cell, shRNA is transcribed and processed bycellular phenomenon to achieve knockout via posttranscriptional level,typically lead to RNA of GOI degradation and/or inefficient translationof GOI. The knockout construct nucleic acid sequence may comprise 1) afull or partial sequence of one or more exons and/or introns of the geneto be suppressed, 2) a full or partial promoter sequence of the gene tobe suppressed, or 3) combinations thereof (See, e.g., Khan, I F et al.,AAV-mediated gene targeting methods for human cells, Nat Protoc.6:482-501 (2011).; Miller, D G, AAV-mediated gene targeting, Methods MolBiol. 807:301-15 (2011).; Grimm, D et al., RNAi and gene therapy: amutual attraction, Hematology Am Soc Hematol Educ Program. 2007:473-81;Nizzardo, M et al., Review: Research advances in gene therapy approachesfor the treatment of amyotrophic lateral sclerosis, Cell Mol Life Sci.69:1641-50 (2012)).

The phrases “disruption of the gene” and “gene disruption” refer toinsertion of a nucleic acid sequence into one region of the native DNAsequence (usually one or more exons) and/or the promoter region of agene so as to decrease or prevent expression of that gene in the cell ascompared to the wild-type or naturally occurring sequence of the gene.By way of example, a nucleic acid construct can be prepared containing aDNA sequence encoding an antibiotic resistance gene which is insertedinto the DNA sequence that is complementary to the DNA sequence(promoter and/or coding region) to be disrupted. When this nucleic acidconstruct is then transfected into a cell, the construct will integrateinto the genomic DNA. Thus, many progeny of the cell will no longerexpress the gene at least in some cells, or will express it at adecreased level, as the DNA is now disrupted by the antibioticresistance gene.

The term “polynucleotide” or “nucleic acid” includes bothsingle-stranded and double-stranded nucleotide polymers containing twoor more nucleotide residues. The nucleotide residues comprising thepolynucleotide can be ribonucleotides or deoxyribonucleotides or amodified form of either type of nucleotide. Such modified forms includebase modifications such as bromouridine and inosine derivatives, ribosemodifications such as 2′,3′-dideoxyribose, and internucleotide linkagemodifications such as phosphorothioate, phosphorodithioate,phosphoroselenoate, phosphorodiselenoate, phosphoroanilothioate,phosphoraniladate and phosphoroamidate.

The term “oligonucleotide” means a polynucleotide comprising 200 orfewer nucleotide residues. In some embodiments, oligonucleotides are 10to 60 bases in length. In other embodiments, oligonucleotides are 12,13, 14, 15, 16, 17, 18, 19, or 20 to 40 nucleotides in length.Oligonucleotides may be single stranded or double stranded, e.g., foruse in the construction of a mutant gene. Oligonucleotides may be senseor antisense oligonucleotides. An oligonucleotide can include a label,including an isotopic label (e.g., ¹²⁵I, ¹⁴C, ¹³C, ³⁵S, ³H, ²H, ¹³N,¹⁵N, ¹⁸O, ¹⁷O, etc.), for ease of quantification or detection, afluorescent label, a hapten or an antigenic label, for detection assays.Oligonucleotides may be used, for example, as PCR primers, cloningprimers or hybridization probes.

A “polynucleotide sequence” or “nucleotide sequence” or “nucleic acidsequence,” as used interchangeably herein, is the primary sequence ofnucleotide residues in a polynucleotide, including of anoligonucleotide, a DNA, a RNA, a nucleic acid, or a character stringrepresenting the primary sequence of nucleotide residues, depending oncontext. From any specified polynucleotide sequence, either the givennucleic acid or the complementary polynucleotide sequence can bedetermined. Included are DNA or RNA of genomic or synthetic origin whichmay be single- or double-stranded, and represent the sense or antisensestrand. Unless specified otherwise, the left-hand end of anysingle-stranded polynucleotide sequence discussed herein is the 5′ end;the left-hand direction of double-stranded polynucleotide sequences isreferred to as the 5′ direction. The direction of 5′ to 3′ addition ofnascent RNA transcripts is referred to as the transcription direction;sequence regions on the DNA strand having the same sequence as the RNAtranscript that are 5′ to the 5′ end of the RNA transcript are referredto as “upstream sequences;” sequence regions on the DNA strand havingthe same sequence as the RNA transcript that are 3′ to the 3′ end of theRNA transcript are referred to as “downstream sequences.” A “nucleicacid” sequence captures sequences that include any of the known baseanalogues of DNA and RNA such as, but not limited to 4-acetylcytosine,8-hydroxy-N-6-methyladenosine, aziridinylcytosine, pseudoisocytosine,5-(carboxyhydroxyl-methyl) uracil, 5-fluorouracil, 5-bromouracil,5-carboxymethylaminomethyl-2-thiouracil,5-carboxymethyl-aminomethyluracil, dihydrouracil, inosine,N6-isopentenyladenine, 1-methyladenine, 1-methylpseudo-uracil,1-methylguanine, 1-methylinosine, 2,2-dimethyl-guanine, 2-methyladenine,2-methylguanine, 3-methyl-cytosine, 5-methylcytosine, N6-methyladenine,7-methylguanine, 5-methylaminomethyluracil,5-methoxy-amino-methyl-2-thiouracil, beta-D-mannosylqueosine,5′-methoxycarbonylmethyluracil, 5-methoxyuracil,2-methylthio-N6-isopentenyladenine, uracil-5-oxyacetic acid methylester,uracil-5-oxyacetic acid, oxybutoxosine, pseudouracil, queosine,2-thiocytosine, 5-methyl-2-thiouracil, 2-thiouracil, 4-thiouracil,5-methyluracil, -uracil-5-oxyacetic acid methylester, uracil-5-oxyaceticacid, pseudouracil, queosine, 2-thiocytosine, and 2,6-diaminopurine.

The term “control sequence” or “control signal”, or interchangeably,“regulatory sequence”, refers to a polynucleotide sequence that can, ina particular host cell, affect the expression and processing of codingsequences. The nature of such control sequences may depend upon the hostorganism. In particular embodiments, control sequences for prokaryotesmay include a promoter, a ribosomal binding site, and a transcriptiontermination sequence. Control sequences for eukaryotes may includepromoters comprising one or a plurality of recognition sites fortranscription factors, polyadenylation signals, transcriptiontermination sequences, upstream regulatory domains, origins ofreplication, internal ribosome entry sites (“IRES”), transcriptionenhancer sequences or elements, and the like, which collectively providefor the replication, transcription and translation of a coding sequencein a recipient cell, polyadenylation sites, and transcriptiontermination sequences. Not all of these control sequences need always bepresent so long as the selected coding sequence is capable of beingreplicated, transcribed and translated in an appropriate host cell.Control sequences can include leader sequences and/or fusion partnersequences. Promoters and enhancers consist of short arrays of DNA thatinteract specifically with cellular proteins involved in transcription(Maniatis, et al., Science 236:1237 (1987)). Promoter and enhancerelements have been isolated from a variety of eukaryotic sourcesincluding genes in yeast, insect and mammalian cells and viruses(analogous control elements, i.e., promoters, are also found inprokaryotes). The selection of a particular promoter and enhancerdepends on what cell type is to be used to express the protein ofinterest. Some eukaryotic promoters and enhancers have a broad hostrange while others are functional in a limited subset of cell types (forreview see Voss, et al., Trends Biochem. Sci., 11:287 (1986) andManiatis, et al., Science 236:1237 (1987)).

The term “promoter” is used herein in its ordinary sense to refer to anucleotide region comprising a DNA regulatory sequence, wherein theregulatory sequence is derived from a gene that is capable of bindingRNA polymerase and initiating transcription of a downstream(3′-direction) coding sequence. Transcription promoters can include“inducible promoters” (where expression of a polynucleotide sequenceoperably linked to the promoter is induced by an analyte, cofactor,regulatory protein, etc.), “repressible promoters” (where expression ofa polynucleotide sequence operably linked to the promoter is induced byan analyte, cofactor, regulatory protein, etc.), and “constitutivepromoters”.

“Operably linked” refers to an arrangement of nucleic acid elementswherein the components so described are configured so as to performtheir usual function. Nucleic acid sequences are “operably linked” insuch a manner that a nucleic acid molecule capable of directing thetranscription of a given gene and/or the synthesis of a desired proteinmolecule is produced. The term also refers to the linkage of amino acidsequences in such a manner so that a functional protein is produced. Forexample, a control sequence in a vector that is “operably linked” to aprotein coding sequence is ligated thereto so that expression of theprotein coding sequence is achieved under conditions compatible with thetranscriptional activity of the control sequences. Thus, controlsequences operably linked to a coding sequence are capable of effectingthe expression of the coding sequence. The control sequences need not becontiguous with the coding sequence, so long as they function to directthe expression thereof. Thus, for example, intervening untranslated yettranscribed sequences can be present between a promoter sequence and thecoding sequence and the promoter sequence can still be considered“operably linked” to the coding sequence.

As used herein, an “isolated nucleic acid molecule” or “isolated nucleicacid sequence” is a nucleic acid molecule that is either (1) identifiedand separated from at least one contaminant nucleic acid molecule withwhich it is ordinarily associated in the natural source of the nucleicacid or (2) cloned, amplified, tagged, or otherwise distinguished frombackground nucleic acids such that the sequence of the nucleic acid ofinterest can be determined. An isolated nucleic acid molecule is otherthan in the form or setting in which it is found in nature. However, anisolated nucleic acid molecule includes a nucleic acid moleculecontained in cells that ordinarily express a polypeptide (e.g., anoligopeptide or antibody) where, for example, the nucleic acid moleculeis in a chromosomal location different from that of natural cells. Thus,an “isolated nucleic acid molecule which encodes a particularpolypeptide” refers to a nucleic acid molecule which is substantiallyfree of other nucleic acid molecules that do not encode the subjectpolypeptide; however, the molecule may include some additional bases ormoieties which do not deleteriously affect the basic characteristics ofthe composition.

For the purpose of describing the relative position of nucleotidesequences in a particular nucleic acid molecule throughout the instantapplication, such as when a particular nucleotide sequence is describedas being situated “upstream,” “downstream,” “5 prime (5′)” or “3 prime(3′)” relative to another sequence, it is to be understood that it isthe position of the sequences in the “sense” or “coding” strand of a DNAmolecule that is being referred to as is conventional in the art.

A “functional homologue,” or a “functional equivalent” of a given AAVpolypeptide includes molecules derived from the native polypeptidesequence, as well as recombinantly produced or chemically synthesizedpolypeptides which function in a manner similar to the reference AAVmolecule to achieve a desired result. Thus, a functional homologue ofAAV Rep68 or Rep78 encompasses derivatives and analogues of thosepolypeptides—including any single or multiple amino acid additions,substitutions and/or deletions occurring internally or at the amino orcarboxy termini thereof—so long as integration activity remains.

By “capable of efficient transduction” is meant that the mutatedconstructs of the invention provide for rAAV vectors or virions thatretain the ability to transfect cells in vitro and/or in vivo at a levelthat is within 1-10% of the transfection efficiency obtained using thecorresponding wild-type sequence. Preferably, the mutant retains theability to transfect cells or tissues at a level that is within 10-100%of the corresponding wild-type sequence. The mutated sequence may evenprovide for a construct with enhanced ability to transfect cells andtissues. Transduction efficiency is readily determined using techniqueswell known in the art, including the in vitro transduction assaydescribed in the Examples.

As used herein, the terms “cell culture medium” and “culture medium”refer to a nutrient solution used for growing mammalian cells in vitrothat typically provides at least one component from one or more of thefollowing categories: 1) an energy source, usually in the form of acarbohydrate such as, for example, glucose; 2) one or more of allessential amino acids, and usually the basic set of twenty amino acidsplus cysteine; 3) vitamins and/or other organic compounds required atlow concentrations; 4) free fatty acids; and 5) trace elements, wheretrace elements are defined as inorganic compounds or naturally occurringelements that are typically required at very low concentrations, usuallyin the micromolar range. The nutrient solution may optionally besupplemented with additional components to optimize growth and/ortransfection of cells.

The mammalian cell culture within the present invention is prepared in amedium suitable for the particular cell being cultured. Suitable cellculture media that may be used for culturing a particular cell typewould be apparent to one of ordinary skill in the art. Exemplarycommercially available media include, for example, Ham's F10 (SIGMA),Minimal Essential Medium (MEM, SIGMA), RPMI-1640 (SIGMA), Dulbecco'sModified Eagle's Medium (DMEM, SIGMA); Iscove modified Dulbecco medium(Gibco) containing 10% fetal bovine serum (see, Xiao et al., Productionof High-Titer Recombinant Adeno-Associated Virus Vectors in the Absenceof Helper Adenovirus, J Virol., 72: 2224-2232 (1998)), and DMEM/F12(Life Technologies). Any of these or other suitable media may besupplemented as necessary with hormones and/or other growth factors(such as but not limited toinsulin, transferrin, or epidermal growthfactor), salts (such as sodium chloride, calcium, magnesium, andphosphate), buffers (such as HEPES), nucleosides (such as adenosine andthymidine), antibiotics (such as puromycin, neomycin, hygromycin,blasticidin, or Gentamycin™), trace elements (defined as inorganiccompounds usually present at final concentrations in the micromolarrange) lipids (such as linoleic or other fatty acids) and their suitablecarriers, and glucose or an equivalent energy source, and/or modified asdescribed herein to facilitate production of recombinant glycoproteinshaving low-mannose content. In a particular embodiment, the cell culturemedium is serum-free.

When defined medium that is serum-free and/or free of proteinhydrolysate (e.g., peptone-free) is used, the medium is usually enrichedfor particular amino acids, vitamins and/or trace elements (see, forexample, U.S. Pat. No. 5,122,469 to Mather et al., and U.S. Pat. No.5,633,162 to Keen et al.). Depending upon the requirements of theparticular cell line used or method, culture medium can contain a serumadditive such as Fetal Bovine Serum, or a serum replacement. Examples ofserum-replacements (for serum-free growth of cells) are TCH™, TM-235™,and TCH™; these products are available commercially from Celox (St.Paul, Minn.), and KOSR (knockout (KO) serum replacement; LifeTechnologies).

In the methods and compositions of the invention, cells can be grown inserum-free, protein-free, growth factor-free, and/or peptone-free media.The term “serum-free” as applied to media in general includes anymammalian cell culture medium that does not contain serum, such as fetalbovine serum (FBS). The term “insulin-free” as applied to media includesany medium to which no exogenous insulin has been added. By exogenous ismeant, in this context, other than that produced by the culturing of thecells themselves. The term “growth-factor free” as applied to mediaincludes any medium to which no exogenous growth factor (e.g., insulin,IGF-1) has been added. The term “peptone-free” as applied to mediaincludes any medium to which no exogenous protein hydrolysates have beenadded such as, for example, animal and/or plant protein hydrolysates.

Optimally, for purposes of the present invention, the culture mediumused is serum-free, or essentially serum-free unless serum is requiredby the inventive methods or for the growth or maintenance of aparticular cell type or cell line. By “serum-free”, it is understoodthat the concentration of serum in the medium is preferably less than0.1% (v/v) serum and more preferably less than 0.01% (v/v) serum. By“essentially serum-free” is meant that less than about 2% (v/v) serum ispresent, more preferably less than about 1% serum is present, still morepreferably less than about 0.5% (v/v) serum is present, yet still morepreferably less than about 0.1% (v/v) serum is present.

“Culturing” or “incubating” (used interchangeably with respect to thegrowth, transformation and/or maintenance of cells or cell lines) isunder conditions of sterility, temperature, pH, atmospheric gas content(e.g., oxygen, carbon dioxide, dinitrogen), humidity, culture container,culture volume, passaging, motion, and other parameters suitable for theintended purpose and conventionally known in the art of mammalian cellculture.

“Polypeptide” and “protein”, or “proteinaceous molecule” are usedinterchangeably herein and include a molecular chain of two or moreamino acids linked covalently through peptide bonds. The terms do notrefer to a specific length of the product. Thus, “peptides,” and“oligopeptides,” are included within the definition of polypeptide. Theterms include post-translational modifications of the polypeptide, forexample, glycosylations, acetylations, phosphorylations and the like. Inaddition, protein fragments, analogs, mutated or variant proteins,fusion proteins and the like are included within the meaning ofpolypeptide. The terms also include molecules in which one or more aminoacid analogs or non-canonical or unnatural amino acids are included ascan be expressed recombinantly using known protein engineeringtechniques. In addition, fusion proteins can be derivatized as describedherein by well-known organic chemistry techniques. The term “fusionprotein” indicates that the protein includes polypeptide componentsderived from more than one parental protein or polypeptide. Typically, afusion protein is expressed from a fusion gene in which a nucleotidesequence encoding a polypeptide sequence from one protein is appended inframe with, and optionally separated by a linker from, a nucleotidesequence encoding a polypeptide sequence from a different protein. Thefusion gene can then be expressed by a recombinant host cell as a singleprotein.

A “domain” or “region” (used interchangeably herein) of a protein is anyportion of the entire protein, up to and including the complete protein,but typically comprising less than the complete protein. A domain can,but need not, fold independently of the rest of the protein chain and/orbe correlated with a particular biological, biochemical, or structuralfunction or location (e.g., a ligand binding domain, or a cytosolic,transmembrane or extracellular domain).

The term “antibody” is used in the broadest sense and includes fullyassembled antibodies, monoclonal antibodies (including human, humanizedor chimeric antibodies), polyclonal antibodies, multispecific antibodies(e.g., bispecific antibodies), and antibody fragments that can bindantigen (e.g., Fab, Fab′, F(ab′)₂, Fv, single chain antibodies,diabodies), comprising complementarity determining regions (CDRs) of theforegoing as long as they exhibit the desired biological activity.Multimers or aggregates of intact molecules and/or fragments, includingchemically derivatized antibodies, are contemplated. Antibodies of anyisotype class or subclass, including IgG, IgM, IgD, IgA, and IgE, IgG1,IgG2, IgG3, IgG4, IgA1 and IgA2, or any allotype, are contemplated.Different isotypes have different effector functions; for example, IgG1and IgG3 isotypes typically have antibody-dependent cellularcytotoxicity (ADCC) activity. Glycosylated and unglycosylated antibodiesare included within the term “antibody”.

The term “host cell” denotes, for example, microorganisms, yeast cells,insect cells, and mammalian cells, that can be, or have been, used asrecipients of an AAV helper construct, an AAV vector plasmid, anaccessory function vector, or other transfer DNA. The term includes theprogeny of the original cell which has been transfected. Thus, a “hostcell” as used herein generally refers to a cell which has beentransfected with an exogenous DNA sequence. It is understood that theprogeny of a single parental cell may not necessarily be completelyidentical in morphology or in genomic or total DNA complement as theoriginal parent, due to natural, accidental, or deliberate mutation. A“mammalian host cell” is a cell originally derived from a mammal or is aprogeny cell thereof.

As used herein, the term “cell line” refers to a population of cellscapable of continuous or prolonged growth and division in vitro. Often,cell lines are clonal populations derived from a single progenitor cell.It is further known in the art that spontaneous or induced changes canoccur in karyotype during storage or transfer of such clonalpopulations. Therefore, cells derived from the cell line referred to maynot be precisely identical to the ancestral cells or cultures, and thecell line referred to includes such variants.

Production of AAV Vectors.

Recombinant AAV virions may be produced using a variety of techniquesknown in the art, including the triple transfection method (described indetail in U.S. Pat. No. 6,001,650, the entirety of which is incorporatedherein by reference). This system involves the use of three vectors forrAAV virion production, including an AAV helper function vector, anaccessory function vector, and a rAAV vector that contains the HNA. Oneof skill in the art will appreciate, however, that the nucleic acidsequences encoded by these vectors can be provided on two or morevectors in various combinations.

The AAV helper function vector encodes the “AAV helper function”sequences (i.e., rep and cap), which function in trans for productiveAAV replication and encapsidation. Preferably, the AAV helper functionvector supports efficient AAV vector production without generating anydetectable wild-type AAV virions (i.e., AAV virions containingfunctional rep and cap genes). Examples of vectors suitable for use withthe present invention include pHLP19, described in U.S. Pat. No.6,001,650 and pRep6cap6 vector, described in U.S. Pat. No. 6,156,303,the disclosure of which is hereby incorporated by reference in itsentirety.

The accessory function vector encodes nucleotide sequences for non-AAVderived viral and/or cellular functions upon which AAV is dependent forreplication (i.e., “accessory functions”). The accessory functionsinclude those functions required for AAV replication, including, withoutlimitation, those moieties involved in activation of AAV genetranscription, stage specific AAV mRNA splicing, AAV DNA replication,synthesis of cap expression products, and AAV capsid assembly.Viral-based accessory functions can be derived from any of the knownhelper viruses such as adenovirus, herpesvirus (other than herpessimplex virus type-1), and vaccinia virus. In a preferred embodiment,the accessory function plasmid pladeno5 is used (details regardingpLadeno5 are described in U.S. Pat. No. 6,004,797, the disclosure ofwhich is hereby incorporated by reference in its entirety). This plasmidprovides a complete set of adenovirus accessory functions for AAV vectorproduction, but lacks the components necessary to formreplication-competent adenovirus.

The rAAV vector containing the heterologous gene of interest (GOI), ornucleic acid (HNA), may be constructed using ITRs from any of thevarious AAV serotypes. The RNA comprises nucleic acid sequences joinedtogether that are otherwise not found together in nature. To illustratethe point, an example of an HNA is a gene flanked by nucleotidesequences not found in association with that gene in nature. Anotherexample of an HNA is a gene that itself is not found in nature (e.g.,synthetic sequences having codons different from the native gene).Allelic variation or naturally occurring mutational events do not giverise to HNAs, as used herein. An HNA can comprise an anti-sense RNAmolecule, a ribozyme, or a gene encoding a polypeptide.

The HNA is operably linked to a heterologous promoter (constitutive,cell-specific, or inducible) such that the HNA is capable of beingexpressed in the ultimate target cells to be transduced by the rAAVvirion (e.g., neurons, lung cells, or liver cells) under appropriate ordesirable conditions. Numerous examples of constitutive, cell-specific,and inducible promoters are known in the art, and one of skill couldreadily select a promoter for a specific intended use, e.g., theselection of the constitutive CMV promoter for strong levels ofcontinuous or near-continuous expression, or the selection of theinducible ecdysone promoter for induced expression. Induced expressionallows the skilled artisan to control the amount of protein that issynthesized. In this manner, it is possible to vary the concentration ofa protein product expressed in a rAAV-transduced mammalian cell, or in anon-human mammal or human patient who may ultimately receive therAAVvirion in gene therapy. Other examples of well known induciblepromoters are: steroid promoters (e.g., estrogen and androgen promoters)and metallothionein promoters.

Selection of a Heterologous Gene(s) of Interest (GOI).

Typically, the GOI(s) or transgene(s) useful in the present inventionwill be a nucleotide sequence encoding a polypeptide of interest, e.g.,a polypeptide involved in the nervous system, an immune response,hematopoiesis, inflammation, cell growth and proliferation, cell lineagedifferentiation, and/or the stress response. The polypeptide can be anenzyme, ion channel, receptor (e.g., a GPCR), hormone, cytokine,chemokine, or an antibody or antibody fragment. Included within thescope of this invention is the insertion of one, two, or more transgenesinto the rAAV virion.

Where more than one transgene is used in this invention, the transgenesmay be prepared and inserted individually, or may be generated togetheras one construct for insertion. The transgenes may be homologous orheterologous to both the promoter selected to drive expression of eachtransgene and/or to the mammal or mammalian cell type ultimatelyintended to be administered the rAAV virion. Further, the transgene maybe a full length cDNA or genomic DNA sequence, or any fragment, subunitor mutant thereof that has at least some biological activity i.e.,exhibits an effect at any level (biochemical, cellular and/ormorphological) that is not readily observed in a wild type,non-transgenic mammal or mammalian cell type of the same species.Optionally, the transgene may be a hybrid nucleotide sequence, i.e., oneconstructed from homologous and/or heterologous cDNA and/or genomic DNAfragments. The transgene may also optionally be a mutant of one or morenaturally occurring cDNA and/or genomic sequences, or an allelic variantthereof.

Each transgene may be isolated and obtained in suitable quantity usingone or more methods that are well known in the art. These methods andothers useful for isolating a transgene are set forth, for example, inSambrook et al. (Molecular Cloning: A Laboratory Manual, Cold SpringHarbor Laboratory Press, Cold Spring Harbor, N.Y. [1989]) and in Bergerand Kimmel (Methods in Enzymology: Guide to Molecular CloningTechniques, vol. 152, Academic Press, Inc., San Diego, Calif. (1987)).

Where the nucleotide sequence of each transgene is known, the transgenemay be synthesized, in whole or in part, using chemical synthesismethods such as those described in Engels et al. (Angew. Chem. Int. Ed.Engl., 28:716-734 [1989]). These methods include, inter alia, thephosphotriester, phosphoramidite and H-phosphonate methods of nucleicacid synthesis. Alternatively, the transgene may be obtained byscreening an appropriate cDNA or genomic library using one or morenucleic acid probes (oligonucleotides, cDNA or genomic DNA fragmentswith an acceptable level of homology to the transgene to be cloned, andthe like) that will hybridize selectively with the transgene DNA.Another suitable method for obtaining a transgene is the polymerasechain reaction (PCR). However, successful use of this method requiresthat enough information about the nucleotide sequence of the transgenebe available so as to design suitable oligonucleotide primers useful foramplification of the appropriate nucleotide sequence.

Where the method of choice requires the use of oligonucleotide primersor probes (e.g. PCR, cDNA or genomic library screening), theoligonucleotide sequences selected as probes or primers should be ofadequate length and sufficiently unambiguous so as to minimize theamount of non-specific binding that will occur during library screeningor PCR. The actual sequence of the probes or primers is usually based onconserved or highly homologous sequences or regions from the same or asimilar gene from another organism. Optionally, the probes or primerscan be degenerate.

In cases where only the amino acid sequence of the transgene is known, aprobable and functional nucleic acid sequence may be inferred for thetransgene using known and preferred codons for each amino acid residue.This sequence can then be chemically synthesized.

This invention encompasses the use of transgene mutant sequences. Amutant transgene is a transgene containing one or more nucleotidesubstitutions, deletions, and/or insertions as compared to the wild typegene sequence. The nucleotide substitution, deletion, and/or insertioncan give rise to a gene product (i.e., protein) that is different in itsamino acid sequence from the wild type amino acid sequence. Preparationof such mutants is well known in the art, and is described for examplein Wells et al. (Gene, 34:315 (1985)), and in Sambrook et al, supra.

Selection of Regulatory Elements.

Transgenes are typically operably linked to promoters, where a promoteris selected to regulate expression of each transgene in a particularmanner.

Where more than one transgene is to be used, each transgene may beregulated by the same or by a different promoter. The selected promotersmay be homologous (i.e., from the same species as the mammalian cell ormammal to be transformed with the transgene) or heterologous (i.e., froma source other than the species of the mammalian cell or mammal to betransformed with the transgene). As such, the source of each promotermay be from any unicellular, prokaryotic or eukaryotic organism, or anyvertebrate or invertebrate organism.

Selection of Other Vector Components

In addition to the transgene and the promoter, the vectors useful forpreparing the transgenes of this invention typically contain one or moreother elements useful for (1) optimal expression of transgene inmammalian cells into which the transgene is inserted, and (2)amplification of the vector in bacterial or mammalian host cells.Amplification of the transgene cassette involves use of an origin ofreplication in the construct suitable to the prokaryotic or mammaliancell host and expression in the cell of rep proteins. Each of theseelements will be positioned appropriately in the vector with respect toeach other element so as to maximize their respective activities. Suchpositioning is well known to the ordinary skilled artisan. The followingelements may be optionally included in the vector as appropriate.

i. Signal Sequence Element

For those embodiments of the invention where the polypeptide encoded bythe transgene is to be secreted, a small polypeptide termed signalsequence is frequently present to direct the polypeptide encoded by thetransgene out of the cell where it is synthesized. Typically, the signalsequence is positioned in the coding region of the transgene towards orat the 5′ end of the coding region. Many signal sequences have beenidentified, and any of them that are functional and thus compatible withthe transgenic tissue may be used in conjunction with the transgene.Therefore, the nucleotide sequence encoding the signal sequence may behomologous or heterologous to the transgene, and may be homologous orheterologous to the ultimately rAAV-transduced mammalian cell ortransgenic mammal receiving the rAAV virion. Additionally, thenucleotide sequence encoding the signal sequence may be chemicallysynthesized using methods set forth above. However, for purposes herein,preferred signal sequences are those that occur naturally with thetransgene (i.e., are homologous to the transgene).

ii. Membrane Anchoring Domain Element

In some cases, it may be desirable to have a transgene expressed on thesurface of a particular intracellular membrane or on the plasma membraneof a rAAV-transduced cell. Naturally occurring membrane proteinscontain, as part of the polypeptide, a stretch of amino acids that serveto anchor the protein to the membrane. However, for proteins that arenot naturally found on the membrane, such a stretch of amino acids maybe added to confer this feature. Frequently, the anchor domain will bean internal portion of the polypeptide sequence and thus the nucleotidesequence encoding it will be engineered into an internal region of thetransgene nucleotide sequence. However, in other cases, the nucleotidesequence encoding the anchor domain may be attached to the 5′ or 3′ endof the transgene nucleotide sequence. Here, the nucleotide sequenceencoding the anchor domain may first be placed into the vector in theappropriate position as a separate component from the nucleotidesequence encoding the transgene. As for the signal sequence, the anchordomain may be from any source and thus may be homologous or heterologouswith respect to both the transgene and the transgenic mammalian celltype or mammal intended to be transformed by the rAAV virion.Alternatively, the anchor domain may be chemically synthesized usingmethods set forth above.

iii. Origin of Replication (“Ori”) Element

This component is typically a part of prokaryotic expression vectorspurchased commercially, and aids in the amplification of the vector in ahost cell. If the vector of choice does not contain an origin ofreplication site, one may be chemically synthesized based on a knownsequence, and ligated into the vector.

iv. Transcription Termination Element

This element, also known as the polyadenylation or polyA sequence, istypically located 3′ to the transgene nucleotide sequence in the vector,and serves to terminate transcription of the transgene. While thenucleotide sequence encoding this element is easily cloned from alibrary or even purchased commercially as part of a vector, it can alsobe readily synthesized using methods for nucleotide sequence synthesissuch as those described above.

v. Intron Element

In many cases, transcription of the transgene is increased by thepresence of one intron or more than one intron (linked by exons) on thecloning vector. The intron(s) may be naturally occurring within thetransgene nucleotide sequence, especially where the transgene is a fulllength or a fragment of a genomic DNA sequence. Where the intron(s) isnot naturally occurring within the nucleotide sequence (as for mostcDNAs), the intron(s) may be obtained from another source. The intron(s)may be homologous or heterologous to the transgene and/or to thetransgenic mammal. The position of the intron with respect to thepromoter and the transgene is important, as the intron must betranscribed to be effective. As such, where the transgene is a cDNAsequence, the preferred position for the intron(s) is 3′ to thetranscription start site, and 5′ to the polyA transcription terminationsequence. Preferably for cDNA transgenes, the intron will be located onone side or the other (i.e., 5′ or 3′) of the transgene nucleotidesequence such that it does not interrupt the transgene nucleotidesequence. Any intron from any source, including any viral, prokaryoticand eukaryotic (plant or animal) organisms, may be used to practice thisinvention, provided that it is compatible with the host cell(s) intowhich it is inserted. Also included herein are synthetic introns.Optionally, more than one intron may be used in the vector. A preferredset of introns and exons is the human growth hormone (hGH) DNA sequence.

vi. Selectable Marker(s) Element

Selectable marker genes encode polypeptides necessary for the survivaland growth of transfected cells grown in a selective culture medium.Typical selection marker genes encode proteins that (a) conferresistance to antibiotics or other toxins, e.g., ampicillin,tetracycline, or kanamycin for prokaryotic host cells, and neomycin,hygromycin, or methotrexate for mammalian cells; (b) complementauxotrophic deficiencies of the cell; or (c) supply critical nutrientsnot available from complex media, e.g., the gene encoding D-alanineracemase for cultures of Bacillus spp., e.g., Bacillusstearothermophilus.

All of the elements set forth above, as well as others useful in thisinvention, are well known to the skilled artisan and are described, forexample, in Sambrook et al. (Molecular Cloning: A Laboratory Manual,Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1989))and Berger et al., eds. (Guide to Molecular Cloning Techniques, AcademicPress, Inc., San Diego, Calif. (1987)).

Construction of Cloning Vectors

The cloning vectors most useful for amplification of pHelper, pTrans,and/or pCis plasmid cassettes useful in this invention are those thatare compatible with prokaryotic cell hosts. However, eukaryotic cellhosts, including mammalian or insect cell hosts, and vectors compatiblewith these cells, are within the scope of the invention.

In certain cases, some of the various elements to be contained on thecloning vector may be already present in commercially available cloningor amplification vectors such as pUC18, pUC19, pBR322, the pGEM vectors(Promega Corp, Madison, Wis.), the pBluescript® vectors such aspBIISK+/− (Stratagene Corp., La Jolla, Calif.), and the like, all ofwhich are suitable for prokaryotic cell hosts. In this case it isnecessary to only insert the transgene(s) into the vector.

However, where one or more of the elements to be used are not alreadypresent on the cloning or amplification vector, they may be individuallyobtained and ligated into the vector. Methods used for obtaining each ofthe elements and ligating them are well known to the skilled artisan andare comparable to the methods set forth above for obtaining a transgene(i.e., synthesis of the DNA, library screening, and the like).

Vectors used for cloning or amplification of the transgene(s) nucleotidesequences and/or for transfection of the mammalian host cells areconstructed using methods well known in the art. Such methods include,for example, the standard techniques of restriction endonucleasedigestion, ligation, agarose and acrylamide gel purification of DNAand/or RNA, column chromatography purification of DNA and/or RNA,phenol/chloroform extraction of DNA, DNA sequencing, polymerase chainreaction amplification, and the like, as set forth in Sambrook et al.,supra.

The final vector used to practice this invention is typicallyconstructed from a starting cloning or amplification vector such as acommercially available vector. This vector may or may not contain someof the elements to be included in the completed vector. If none of thedesired elements are present in the starting vector, each element may beindividually ligated into the vector by cutting the vector with theappropriate restriction endonuclease(s) such that the ends of theelement to be ligated in and the ends of the vector are compatible forligation. In some cases, it may be necessary to “blunt” the ends to beligated together in order to obtain a satisfactory ligation. Blunting isaccomplished by first filling in “sticky ends” using Klenow DNApolymerase or T4 DNA polymerase in the presence of all four nucleotides.This procedure is well known in the art and is described for example inSambrook et al., supra.

Alternatively, two or more of the elements to be inserted into thevector may first be ligated together (if they are to be positionedadjacent to each other) and then ligated into the vector.

One other method for constructing the vector is to conduct all ligationsof the various elements simultaneously in one reaction mixture. Here,many nonsense or nonfunctional vectors will be generated due to improperligation or insertion of the elements, however the functional vector maybe identified and selected by restriction endonuclease digestion.

After the vector has been constructed, it may be transfected into aprokaryotic host cell for amplification. Cells typically used foramplification are E. coli DH5-alpha (Gibco/BRL, Grand Island, N.Y.) andother E. coli strains with characteristics similar to DH5-alpha.

Where mammalian host cells are used, cell lines such as human embryonickidney cells (e.g., HEK 293) or Chinese hamster ovary (CHO cells; Urlabet al., Proc. Natl. Acad. Sci USA, 77:4216 (1980)) and human embryonickidney cell line 293 (Graham et al., J. Gen. Virol., 36:59 (1977)), aswell as other lines, are suitable.

Transfection of the vector into the selected host cell line foramplification is accomplished using such methods as calcium phosphate,electroporation, microinjection, lipofection or DEAE-dextran. The methodselected will in part be a function of the type of host cell to betransfected. These methods and other suitable methods are well known tothe skilled artisan, and are set forth in Sambrook et al., supra.

After culturing the cells long enough for the vector to be sufficientlyamplified (usually overnight for E. coli cells), the vector (oftentermed plasmid at this stage) is isolated from the cells and purified.Typically, the cells are lysed and the plasmid is extracted from othercell contents. Methods suitable for plasmid purification include interalia, the alkaline lysis mini-prep method (Sambrook et al., supra).

Preparation of Plasmid for Insertion

Typically, the plasmid containing the transgene is linearized, andportions of it removed using a selected restriction endonuclease priorto insertion into the mammalian host cell. In some cases, it may bepreferable to isolate the transgene, promoter, and regulatory elementsas a linear fragment from the other portions of the vector, therebyinjecting only a linear nucleotide sequence containing the transgene,promoter, intron (if one is to be used), enhancer, polyA sequence, andoptionally a signal sequence or membrane anchoring domain into themammalian host cell. This may be accomplished by cutting the plasmid soas to remove the nucleic acid sequence region containing these elements,and purifying this region using agarose gel electrophoresis or othersuitable purification methods.

Recombinant Production of Polypeptides of Interest.

Relevant amino acid sequences from a polypeptide of interest (e.g., animmunoglobulin) may be determined by direct protein sequencing, andsuitable encoding nucleotide sequences can be designed according to auniversal codon table. Alternatively, genomic or cDNA encoding themonoclonal antibodies may be isolated and sequenced from cells producingsuch antibodies using conventional procedures (e.g., by usingoligonucleotide probes that are capable of binding specifically to genesencoding the heavy and light chains of the monoclonal antibodies).Relevant DNA sequences can be determined by direct nucleic acidsequencing.

Cloning of DNA is carried out using standard techniques (see, e.g.,Sambrook et al. (1989) Molecular Cloning: A Laboratory Guide, Vols 1-3,Cold Spring Harbor Press, which is incorporated herein by reference).For example, a cDNA library may be constructed by reverse transcriptionof polyA+mRNA, preferably membrane-associated mRNA, and the libraryscreened using probes specific for human immunoglobulin polypeptide genesequences. In one embodiment, however, the polymerase chain reaction(PCR) is used to amplify cDNAs (or portions of full-length cDNAs)encoding an immunoglobulin gene segment of interest (e.g., a light orheavy chain variable segment). The amplified sequences can be readilycloned into any suitable vector, e.g., expression vectors, minigenevectors, or phage display vectors. It will be appreciated that theparticular method of cloning used is not critical, so long as it ispossible to determine the sequence of some portion of the gene productof interest.

For example, one source for antibody nucleic acids is a hybridomaproduced by obtaining a B cell from an animal immunized with the antigenof interest and fusing it to an immortal cell. Alternatively, nucleicacid can be isolated from B cells (or whole spleen) of the immunizedanimal. Yet another source of nucleic acids encoding antibodies is alibrary of such nucleic acids generated, for example, through phagedisplay technology. Polynucleotides encoding peptides of interest, e.g.,variable region peptides with desired binding characteristics, can beidentified by standard techniques such as panning. The sequence encodingan entire variable region of the immunoglobulin polypeptide may bedetermined; however, it will sometimes be adequate to sequence only aportion of a variable region, for example, the CDR-encoding portion.Sequencing is carried out using standard techniques (see, e.g., Sambrooket al. (1989) Molecular Cloning: A Laboratory Guide, Vols 1-3, ColdSpring Harbor Press, and Sanger, F. et al. (1977) Proc. Natl. Acad. Sci.USA 74: 5463-5467, which is incorporated herein by reference). Bycomparing the sequence of the cloned nucleic acid with publishedsequences of human immunoglobulin genes and cDNAs, one of skill willreadily be able to determine, depending on the region sequenced, (i) thegermline segment usage of the hybridoma immunoglobulin polypeptide(including the isotype of the heavy chain) and (ii) the sequence of theheavy and light chain variable regions, including sequences resultingfrom N-region addition and the process of somatic mutation. One sourceof immunoglobulin gene sequence information is the National Center forBiotechnology Information, National Library of Medicine, NationalInstitutes of Health, Bethesda, Md. Isolated DNA can be operably linkedto control sequences or placed into expression vectors, which are thentransfected into host cells that do not otherwise produce immunoglobulinprotein, to direct the synthesis of monoclonal antibodies in therecombinant host cells. Recombinant production of antibodies is wellknown in the art.

Nucleic acid is operably linked when it is placed into a functionalrelationship with another nucleic acid sequence. For example, DNA for apresequence or secretory leader is operably linked to DNA for apolypeptide if it is expressed as a preprotein that participates in thesecretion of the polypeptide; a promoter or enhancer is operably linkedto a coding sequence if it affects the transcription of the sequence; ora ribosome binding site is operably linked to a coding sequence if it ispositioned so as to facilitate translation. Generally, operably linkedmeans that the DNA sequences being linked are contiguous, and, in thecase of a secretory leader, contiguous and in reading phase. However,enhancers do not have to be contiguous. Linking is accomplished byligation at convenient restriction sites. If such sites do not exist,the synthetic oligonucleotide adaptors or linkers are used in accordancewith conventional practice.

Many vectors are known in the art. Vector components may include one ormore of the following: a signal sequence (that may, for example, directsecretion of the polypeptide of interest, e.g., an antibody. An exampleof a signal sequence is:

ATGGACATGAGGGTGCCCGCTCAGCTCCTGGGGCTCCTGCTGCTGTGGC TGAGAGGTGCGCGCTGT//SEQID NO:1, which encodes the VK-1 signal peptide sequenceMDMRVPAQLLGLLLLWLRGARC//SEQ ID NO:2), an origin of replication, one ormore selective marker genes (that may, for example, confer antibiotic orother drug resistance, complement auxotrophic deficiencies, or supplycritical nutrients not available in the media), an enhancer element, apromoter, and a transcription termination sequence, all of which arewell known in the art.

“Cell”, “cell line”, and “cell culture” are often used interchangeablyand all such designations herein include progeny. Transformants andtransformed cells include the primary subject cell and cultures derivedtherefrom without regard for the number of transfers. It is alsounderstood that all progeny may not be precisely identical in DNAcontent, due to deliberate or inadvertent mutations. Mutant progeny thathave the same function or biological activity as screened for in theoriginally transformed cell are included.

Exemplary mammalian host cells include mammalian host cells thatcomprise a functional adenoviral E1A gene, either as a component of theparental cell line, such as in HEK 293, or by way of transformation of adifferent cell line of interest to include functionally expressedadenoviral E1A, and recombinant production of rAAV virions and otherpolypeptides of interest (including antibody) from such cells has becomeroutine procedure. Other examples of useful mammalian host cell linesare Chinese hamster ovary cells, including CHOK1 cells (ATCC CCL61),DXB-11, DG-44, and Chinese hamster ovary cells/-DHFR (CHO, Urlaub etal., Proc. Natl. Acad. Sci. USA 77: 4216 (1980)); monkey kidney CV1 linetransformed by SV40 (COS-7, ATCC CRL 1651); human embryonic kidney line(293 or 293 cells subcloned for growth in suspension culture, [Graham etal., J. Gen Virol. 36: 59 (1977)]; baby hamster kidney cells (BHK, ATCCCCL 10); mouse sertoli cells (TM4, Mather, Biol. Reprod. 23: 243-251(1980)); monkey kidney cells (CV1 ATCC CCL 70); African green monkeykidney cells (VERO-76, ATCC CRL-1587); human cervical carcinoma cells(HELA, ATCC CCL 2); canine kidney cells (MDCK, ATCC CCL 34); A549 cells(ATCC® CCL-185™; adenocarcinomic human alveolar basal epithelial cells;see, Farson et al., Development and characterization of a cell line forlarge-scale, serum-free production of recombinant adeno-associated viralvectors, J Gene Med. 6(12):1369-81 (2004)); buffalo rat liver cells (BRL3A, ATCC CRL 1442); human lung cells (W138, ATCC CCL 75); human hepatomacells (Hep G2, HB 8065); mouse mammary tumor (MMT 060562, ATCC CCL51);TRI cells (Mather et al., Annals N.Y Acad. Sci. 383: 44-68 (1982)); MRC5 cells or FS4 cells; or mammalian myeloma cells.

Mammalian host cells are transformed or transfected with theabove-described nucleic acids or vectors for production of rAAV virionsand, optionally other polypeptides of interest (including antibodies orantibody fragments, enzymes, hormones, cytokines, chemokines, receptors,etc.), and are cultured in conventional nutrient media modified asappropriate for inducing promoters, selecting transformants, oramplifying the genes encoding the desired sequences. In addition, novelvectors and transfected cell lines with multiple copies of transcriptionunits separated by a selective marker are particularly useful for theexpression of polypeptides.

The mammalian host cells used to produce the recombinant AAV virionsaccording to the invention may be cultured in a variety of media.Commercially available media such as Ham's F10 (Sigma), MinimalEssential Medium ((MEM), (Sigma), RPMI-1640 (Sigma), and Dulbecco'sModified Eagle's Medium ((DMEM), Sigma) are suitable for culturing thehost cells. In addition, any of the media described in Ham et al., Meth.Enz. 58: 44 (1979), Barnes et al., Anal. Biochem. 102: 255 (1980), U.S.Pat. No. 4,767,704; 4,657,866; 4,927,762; 4,560,655; or 5,122,469;WO90103430; WO 87/00195; or U.S. Pat. Re. No. 30,985 may be used asculture media for the host cells. Any of these media may be supplementedas necessary with hormones and/or other growth factors (such as insulin,transferrin, or epidermal growth factor), salts (such as sodiumchloride, calcium, magnesium, and phosphate), buffers (such as HEPES),nucleotides (such as adenosine and thymidine), antibiotics (such asGentamycin™ drug), trace elements (defined as inorganic compoundsusually present at final concentrations in the micromolar range), andglucose or an equivalent energy source. Any other necessary supplementsmay also be included at appropriate concentrations that would be knownto those skilled in the art. The culture conditions, such astemperature, pH, and the like, are those previously used with the hostcell selected for expression, and will be apparent to the ordinarilyskilled artisan.

Upon culturing the host cells, the recombinant polypeptide can beproduced intracellularly, in the periplasmic space, or directly secretedinto the medium. If the polypeptide, such as an antibody, is producedintracellularly, as a first step, the particulate debris, either hostcells or lysed fragments, is removed, for example, by centrifugation orultrafiltration.

Recombinant AAV virions and other polypeptides of interest, such as butnot limited to, an antibody or antibody fragment, enzyme, ion channel,hormone, cytokine, chemokine, receptor, or toxin peptide) can bepurified using, for example, hydroxylapatite chromatography, Sepharose®chromatography, cation or anion exchange chromatography, or preferablyaffinity chromatography, using the antigen of interest or protein A orprotein G as an affinity ligand. Protein A can be used to purifyproteins that include polypeptides that are based on human γ1, γ2, or γ4heavy chains (Lindmark et al., J. Immunol. Meth. 62: 1-13 (1983)).Protein G is recommended for all mouse isotypes and for human γ3 (Gusset al., EMBO J. 5: 15671575 (1986)). The matrix to which the affinityligand is attached is most often agarose, but other matrices areavailable. Mechanically stable matrices such as controlled pore glass orpoly(styrenedivinyl)benzene allow for faster flow rates and shorterprocessing times than can be achieved with agarose. Where the proteincomprises a C_(H)3 domain, the Bakerbond ABX™ resin (J. T. Baker,Phillipsburg, N.J.) is useful for purification. Other techniques forprotein purification such as ethanol precipitation, Reverse Phase HPLC,chromatofocusing, SDS-PAGE, and ammonium sulfate precipitation are alsopossible depending on the antibody to be recovered. Other purificationmethods useful in practicing the invention are known in the art ordescribed herein.

Examples of embodiments of the invention include the following:

Embodiment 1

An in vitro method of producing a recombinant AAV virion in a mammalianhost cell, comprising incubating the cell in a transfection mediumcomprising:

(i) an accessory construct comprising a plasmid (pHelper) comprisingadenoviral E2, E4Orf6, and VAI RNA genes operably linked to an origin ofreplication element and one or more other regulatory sequences;

(ii) an AAV helper construct comprising a plasmid (pTrans) comprisingAAV rep and AAV cap coding regions operably linked to one or moreregulatory sequences; and

(iii) a AAV vector comprising a plasmid (pCis), comprising AAV invertedterminal repeats flanking a heterologous gene of interest operablylinked to one or more regulatory sequences,

wherein the ratio of pHelper:pTrans:pCis is 1:1 to 5:0.009 to 0.36(weight:weight:weight).

Embodiment 2

The method of Embodiment 1, wherein the mammalian host cell is a HEK 293cell.

Embodiment 3

The method of Embodiment 2, wherein the HEK 293 cell is suspended in thetransfection medium.

Embodiment 4

The method of Embodiment 3, wherein the HEK 293 cell is suspended at acell density of 2.1-3.0×10⁶ cells/mL.

Embodiment 5

The method of Embodiment 4, wherein the HEK 293 cell is suspended at acell density of 2.2-2.7×10⁶ cells/mL.

Embodiment 6

The method of Embodiment 5, wherein the HEK 293 cell is suspended at acell density of about 2.5×10⁶ cells/mL.

Embodiment 7

The method of Embodiments 1-2, wherein the cell adheres to a solidsubstrate.

Embodiment 8

The method of Embodiment 1, wherein transfection medium comprisestryptone N1 (TN1) at a concentration of 1.4-1.6% (w/v).

Embodiment 9

The method of Embodiment 8, wherein the tryptone N1 (TN1) is at aconcentration of 1.475-1.525% (w/v).

Embodiment 10

The method of Embodiments 1-9, wherein the transfection medium comprises0-20 mM sodium butyrate.

Embodiment 11

The method of Embodiments 1-10, wherein the ratio of pHelper:pTrans:pCisis 1:1 to 5:0.30 to 0.36 (weight:weight:weight).

Embodiment 12

The method of Embodiment 11, wherein the ratio of pHelper:pTrans:pCis is1:5:0.31 (weight:weight:weight).

Embodiment 13

A recombinant AAV virion made by the method of any of Embodiments 1-12.

The invention will be more fully understood by reference to thefollowing examples. These examples are not to be construed in any way aslimiting the scope of this invention.

EXAMPLES Example 1 Materials and Methods

Cell Culture:

Suspension HEK293T cells were cultured in a 125-ml Erlenmeyer flask(Corning) agitated at 110 rpm. HEK293T cells were grown in 20 ml ofFreeStyle™ 293 Expression Medium (Life Technologies; Durocher et al.,Scalable serum-free production of recombinant adeno-associated virustype 2 by transfection of 293 suspension cells, J Virol Methods144:32-40 (2007)) supplemented with 2% FBS and 50 mg/L G418, and 293-6Ecells were cultured in FreeStyle™ F17 Expression Medium (LifeTechnologies) supplemented with 6 mM glutamine, 0.1% F68 and 25 mg/LG418. For rAAV vector production in large scale, cells were cultured in1 L of the same medium in a 3 L Erlenmeyer flask agitating at 65 rpm.Adherent HEK293T cells were cultured in DMEM medium supplemented with10% FBS (Luk et al., Efficient Serotype-Dependent Release of FunctionalVector into the Culture Medium During Adeno-Associated VirusManufacturing, Efficient Serotype-Dependent Release of Functional Vectorinto the Culture Medium During Adeno-Associated Virus Manufacturing, HumGene Ther. 21: 1251-1257 (2010)) and penicillin (100 units/mL),streptomycin (100 μg/mL), and glutamine (0.292 mg/mL).

Plasmid Construction:

pTrans2 was generated by subcloning of the DNA fragment encoding the repand cap ORF from the AAV2 genome into pBluescript II (AgilentTechnologies) and modifications were introduced upstream of the rep ORFto enhance AAV cap gene expression. The pTrans2/8 and pAGL2/8 wereconstructed by replacing the cap ORF in pTrans2 and pAAV-RC with theAAV8 cap ORF, respectively.

Recombinant AAV Vector Production in Suspension Cells:

Cells were transfected using PEIMAX (Polyscience) with three plasmids(pHelper, pTrans and pCis-EGFP). Brief maps of the plasmids are shown inFIG. 1. Plasmids were mixed in OptiMEM (Life Technologies, 1/20 volumeof the cells to be transfected) and incubated for 5 min. PEIMAX was thenadded to DNA diluted in OptiMEM, and, after incubation for an additional10 min, the DNA-PEIMAX complex was added to the cells. Twenty four hourspost transfection, sodium butyrate and protein hydrolysate (in this caseTryptone N1 [TN1], a controlled enzymatic hydrolysis of casein;Organotechnie® S.A.S.; see, Pham et al., Biotechnol Bioeng 90: 332-344(2005])) were added to the culture, and rAAV vectors were harvested 72 hpost transfection. For large scale production of rAAV2/8 vectors,rAAV2/8 vectors in both the cells and medium were harvested.

Recombinant AAV Vector Production in Adherent Cells:

For large scale rAAV vector production, cells in a CellSTACK® cellculture chamber (CS, 10 layers, 6360 cm², Corning) were transfected with4 mg (plasmid ratio 2:1:1), or 3 mg (plasmid ratio 1:5:0.31) of totalDNA using a CaPO₄ method in 2 L of DMEM with 2% fetal bovine serum(FBS), penicillin (100 units/mL), streptomycin (100 μg/mL), andglutamine (0.292 mg/mL). After 24 hours, the transfection medium wasreplaced with 1 L of fresh DMEM supplemented with TN1 and sodiumbutyrate, and rAAV2/8 vectors in cells and medium were harvested at 72hours post transfection.

Purification of rAAV2/1, 2, 2/5, and 2/8 Vectors:

For large scale production, rAAV2/8 vectors in the medium wereprecipitated as previously described with polyethylene glycol (PEG)(Sigma) and NaCl, and cells were lysed by freezing/thawing 3 times. Thecell lysate and medium were then combined (the starting material), andadjusted to pH 5.5 to precipitate proteins. After centrifugation at12000 g, the pH was adjusted to 8.0 and the starting material wasfiltered through a 0.2 μm filter. The rAAV vectors were then loaded ontoan AVB Sepharose column and eluted with Glycine-HCl (pH 3.0). The elutedrAAV vector was immediately neutralized with 1M Tris-HCl (pH 8.0) anddialyzed against phosphate buffered saline (PBS)-MK buffer (PBS with 1mM MgCl₂ and 2.5 mM KCl). Purified rAAV vectors were then concentratedto a desired concentration in dialysis cassettes with Slide-A-LyzerConcentrating Solution (Thermo Fisher).

DNA Dot Blot Analysis:

Cell lysates were loaded onto Nylon membrane and hybridized overnightwith a ³²P-labeled EF1α promoter specific probe. After washing, theintensity of radioactivity was measured using a Storm A60 Scanner.

rAAV Titration Using CyQuant:

Purified rAAV2/8 vectors from large scale production were routinelytitered using the QuickTiter AAV Quantitation Kit (Cell Biolabs, INC).

rAAV Titration Using bDNA Assay:

For quantification of rAAV2/1, 2, 2/5, or 2/8 produced in 20 mlcultures, rAAVs in cell lysates were first purified with AVB Sepharose,and then the QuantiGene2.0 assay (Branched DNA Technology) was used todetermine the GCs of rAAV using a rAAV prep with known viral GC asstandard. The EF1α and the CMV promoter specific probe sets forpCis-EGFP, pAAV-LacZ, and pAAV-empty were used. Serially diluted viralpreps were incubated in lysis buffer with a specific probe set in bDNAcapture plates at 55° C. for overnight hybridization and thenchemiluminescent signals were read in a Perkin Elmer EnVision aspreviously reported.

Statistical Method:

All experimental designs and statistical analyses were performed usingJMP version 7.0.2 and version 9.0.0 under the Windows Vista System. Forthe purpose of characterizing the impact of cell density, total DNAamount, ratio of Plasmid 1 (pHelper) to Plasmid2 (pTrans) and ratio ofPlasmid 1 to Plasmid 3 (pCis) on the production of rAAV2/8 vector insuspension HEK293T cells and maximizing such production with regard tothese factors with TN1 and sodium butyrate fixed. Two response surfacedesign experiments (40 runs fixing Ratio of PEIMAX to total DNA amount)were performed and statistically analyzed. For the purpose of improvingproduction of rAAV2/8 vector in HEK293T suspension cells with regard toTN1 and sodium butyrate given the factor levels determined from previoustwo response surface experiments, a response surface experiment (28runs) was performed and statistically analyzed.

SDS-PAGE and Immunoblot:

Proteins in cell lysates were separated on a 4-20% reducing Tris-Glycinegel (Life Technologies). Following transfer, membranes were probed withanti-VP1, 2, 3 mAb (Fitzgerald Industries Inc.) and incubated with AlexaFluor 680 goat anti-mouse IgG (Life Technologies). Protein bands werevisualized on an Odyssey Scanner (LiCor).

Example 2 Improvement of rAAV Vector Production

We improved rAAV2/8 vector production by employing adesign-of-experiment (DOE) multivariable analysis approach. The DOEapproach can be advantageous over the one-factor-at-a-time (OFAT) methodbecause it requires fewer resources (experiments, time, material, etc.)for the amount of information obtained. Also, the estimates of theeffects of each factor are more precise and the interaction betweenfactors can be estimated systematically.

1. Improved parameters from an OFAT method for rAAV2/5 vector productiondid not yield efficient rAAV2/8 vector production. We improved rAAV2/5production in suspension HEK293T cells using an OFAT method. This studyof rAAV2/5 vector production revealed the optimal parameter values ofcell density at 0.5×10⁵ cells/ml, plasmid concentration at 1.5 μg/ml,and harvest time at 72 h, similar to the published methods for rAAV2vector productions (Durocher Y, Pham P L, St-Laurent G, Jacob D, Cass B,Chahal P, Lau C J, Nalbantoglu J, Kamen A. Scalable serum-freeproduction of recombinant adeno-associated virus type 2 by transfectionof HEK293 suspension cells. J. Virol. Methods. 144:32-40 (2007)). Wealso demonstrated that addition of Tryptone N1 (TN1) and sodium butyrate24 hours after transfection increased rAAV2/5 vector production based onImmunoblot analysis for AAV5 capsid proteins (VP1, VP2 and VP3). Byusing these optimal conditions in suspension cells, we achieved rAAV2/5vector GC production levels equivalent to those from adherent HEK293Tcells (Zhao H, Wolf T, van der Valk M, Plewa C A, Sheng J, Lee K J. Costeffective and facile method of rAAV production in suspension-adaptedHEK293 cells. Mol. Ther. 19, Supplement 1:S257 (2011)). However, whenthese optimal conditions were applied to rAAV2/8 vector production,production yields were much lower than those from adherent HEK 293Tcells based on both Immunoblot analysis of VPs in the cell lysate (FIG.2A) and quantification of genome copies (GC) after purification with AVBSepharose (FIG. 2B). Initial attempts at improving rAAV2/8 vectorproduction using the OFAT method was not successful (data not shown).Thus, a design-of-experiment (DOE) multivariable analysis approach wasemployed for improvement of rAAV2/8 vector production.

2. Production yield of rAAV2/8 vector by a DOE-improved method insuspension cells is comparable to adherent cells and uses a lower amountof DNA. We studied a variety of parameters using a DOE approach,including cell density, total amount of DNA, and plasmid ratios(pHelper:pTrans2/8 and pHelper:pCis-eGFP). The ranges of theseparameters used for experimental design are shown in Table 1 below.

TABLE 1 Design of experiment (DOE). All transfections were carried outin 125-ml Erlenmeyer flasks. Transfection volume was 20 ml. Forty runsinclude duplicates. Parameters Variation ranges Cell density (×10⁶/ml)0.25-4.0  Total amount of DNA (mg/L) 0.5-3.5 pHelper:pTrans2/8  1:5-1:0.2 pHelper:pCis-EGFP   1:5-1:0.16 PEIMAX:DNA 3:1 (fixed)Trypton N1 (TN1) 0.5% w/v (fixed) Sodium Butyrate 5 mM (fixed)

The ratio of PEIMAX to the amount of DNA (3:1) is well established andtherefore was not studied here. TN1 and sodium butyrate were included asthese additives promoted capsid protein expression in our previous OFAToptimization for rAAV2/5 vector production and were kept constant in thedesign to reduce the number of variables and runs (Zhao H, Wolf T, vander Valk M, Plewa C A, Sheng J, Lee K J. Cost effective and facilemethod of rAAV production in suspension-adapted HEK293 cells. Mol. Ther.19, Supplement 1:S257 (2011)). The study employing a DOE approach wascarried out in 20 ml of suspension HEK293T cells using enhanced greenfluorescence protein (eGFP) as the gene of interest (GOI). TN1 andsodium butyrate were added 24 h post transfection. The GCs of rAAV2/8vectors in the cell lysate were determined by Dot blot analysis, and thedata were analyzed with JMP software. DOE revealed a novel set ofparameter values as compared to both published and our ownOFAT-optimized methods for rAAV2/5 production (Table 2; below).

TABLE 2 Comparison of optimal values of DOE with published rAAV2 andexperimental rAAV2/5 vector production conditions. ExperimentalExperimental Published Suspension Suspension susp. Conditions ConditionsExperimental conditions* rAAV2/5 rAAV2/8 cell stack Factors rAAV2(OFAT)^(&) (DOE) conditions Cell density 0.5-1 0.5 2.45 N/A (×10⁶/mL)DNA 1-1.25 mg/L 1.5 mg/L 1.5 mg/L 4 mg/6300 amount cm² Plasmid 1:1:1 or2:1:1 2:1:1 1:5:0.31 2:1:1 ratio*^(#) PEI:DNA 2:1, 3:1 3:1 3:1 N/A(CaPO₄) N/A = not applicable; *Hildinger, M., et al. Biotechnol. Lett.2007; 29: 1713-172, Durocher Y., et al. J. Virol. Methods 2007; 144:32-40; ^(#)Plasmid ratio: pHelper:pTrans:pCis; & Zhao, H. et al., Mol.Ther. 19, Supplement 1:S257 (2011).

Notably, the innovative plasmid ratio 1:5:0.31 (pHelper:pTrans:pCis,weight:weight) is divergent from published ratios reported for adherentcells (1:1:1 or 2:1:1) or for suspension cells (1:1:1 or 3:1:1); and thecell density (2.45×10⁶ cells/ml) is higher than in published methods(0.5-1×10⁶ cells/ml). These parameter values were then used to producerAAV2/8-eGFP in 1 L scale, and the yield (GC/L) was determined using theCyQuant titration method. As shown in FIG. 3A, the amount ofrAAV2/8-eGFP produced in 1 L suspension is comparable to that from a10-layer CellSTACK® cell culture chamber (6360 cm²). This method wasthen applied to large scale productions for many GOIs. As shown in FIG.3B, average production yields were equivalent to those from adherentHEK293T cells. In addition to the higher yield than that from the OFAToptimized protocol (FIG. 2B), the combination of lower total DNA amountand the novel plasmid ratio allows us to reduce the of total amount ofDNA to 62.5% of previous, 92.6% of pCis-GOI and 88.1% of pHelper ascompared to the amounts used for adherent cells (FIG. 3C). Reduction ofthe amount of pHelper and pCis-GOI used in rAAV2/8 vector productionwill significantly ease the process.

3. The novel plasmid ratio revealed by the DOE analysis in suspensioncells can also be applied to adherent cells. To test if the novelplasmid ratio can be used for rAAV production in adherent HEK293T cells,we transfected adherent HEK293T cells in a 10-layer CellSTACK® cellculture chamber using a calcium phosphate protocol with either theexisting plasmid ratio (2:1:1, pHelper:pTrans:pCis, total 4 mg DNA in 2L of medium [2 mg/L]) or the newly established plasmid ratio (1:5:0.31,total 3 mg DNA in 2 L of medium [1.5 mg/L]). The medium was replacedwith 1 L fresh medium 24 h post transfection. Production yields with thenew plasmid ratio were comparable to the standard protocol as judged bytotal GC (FIG. 4A). Again, the major advantage of using the new plasmidratio is significant reduction of the amount of total DNA (down 25%),pHelper (down 76%) and pCis-GOI (down 85%), while the amount of pTranswas increased considerably (up 138%, FIG. 4B). The amount of plasmidsused in rAAV vector production using either suspension or adherent cellsfrom previously published and Amgen's in house data are summarized inFIG. 5.

4. The improved production protocol determined for serotype 8 can alsobe applied to rAAV 2/1, 2, 2/5 and 2/9 serotypes produced in suspensioncells. Next we attempted to determine if the DOE-improved method couldbe used for production of other rAAV serotypes besides rAAV2/8, e. g.rAAV2/1, 2, 2/5, and 2/9. To this end, rAAV2/1, 2, 2/5, and 2/9 weregenerated in 20 ml of suspension HEK293T cells using either theDOE-improved protocol or our previously described OFAT-optimizedprotocol for rAAV2/5 vector production (Table 2). The total GCs andcapsid proteins in the lysates were analyzed by bDNA assay andImmunoblot, respectively. As shown in FIG. 6A, significantly more GCswere produced using the DOE-improved method for rAAV2/1 (4.5 times), 2/2(1.7 times) and 2/8 (17 times). Similar trends were observed when vectorproduction was quantified by Immunoblot (FIG. 6B). Since rAAV2/9 vectorsdo not bind to AVB Sepharose (data not shown), we were unable to purifyand analyze them by bDNA assay. Therefore, we relied solely on theImmunoblot assay for quantitation of production. Again, more rAAV2/9capsid proteins were detected in samples produced using the DOE-improvedprotocol than that in those produced using the OFAT-optimized protocol.There was variability in the total production yields of rAAV2/8 vectorsbetween experiments although the DOE-improved method resulted inconsistently higher production yields (FIG. 6A: 17 folds and FIG. 2A:5-6 folds). The variability could be due to slight differences inproduction and/or purification scales or the titration methods used inthese experiments. Overall production yield using the DOE-improvedprotocol is superior to that from the OFAT-optimized protocol,especially for rAAV2/1 and 2/8 production. It will be interesting toknow if these findings can be extended to other serotypes such as AAV3,4, 6, and 7.

5. Using plasmid ratios predicted to be greater than 90% of the maximalproduction of rAAV vector yields similar amount of rAAV vector ascompared to the DOE-improved ratio. Since the plasmid ratio identifiedusing DOE optimization is unique compared to other published ratios, wetried to define the range of ratios that produce similar amounts ofvector to using the optimal value. First, we calculated the range ofplasmid ratios resulting in production yields within 90%, 80%, and 70%of the optimal ratio (see, Table 3A; below). Then we experimentallytested the production yields using the plasmid ratios predicted toproduce 90% of the optimal yield, while keeping the total amount DNA(1.5 μg/ml) unchanged (see, Table 3B, below). As shown in FIG. 7,production yields of rAAV2/8-eGFP obtained from these ratios weresimilar to those from the optimal ratios. In the case of rAAV2-eGFPproduction, slightly more rAAV2 vector was produced with the ratio of1:1:0.31, possibly because the original optimization was for rAAV2/8,not rAAV2. These results suggest that a broader range of plasmid ratioscould result in similar enhanced production yields of rAAV.

TABLE 3A Predicted range of parameters for 90%, 80%, and 70% of optimalrAAV8 production. Plasmid ratios are based on weight 70% 80% 90%Parameters range range range Optimal DNA amount 1.5-2.1 1.5-2.3 1.5-2.31.5 (μg/mL) Cell density 1.2-3.8 1.15-3.6  1.4-3.7 2.45 (×10⁶/mL)pHelper:pTrans 0.2-2.5 0.2-1.5 0.2-1   0.2 pHelper:pCis 1.9-3.9 2.7-3.52.8-3.3 3.23

TABLE 3B Plasmid ratios predicted to produce 90% of the optimal yieldPlasmid ratio Parameters of 90% range pHelper:pTrans 1:5:0.31 1:5:0.36pHelper:pCis 1:1:0.31 1:1:0.36

6. The DOE-improved protocol can be used with Agilent's plasmid systemfor rAAV2/8 vector production, but not rAAV2. As described in Materialsand Methods, the pTrans plasmid used in our studies is extensivelymodified (and different from pACG2). To broaden the application of ournewly established protocol to rAAV plasmids systems beyond our own, wetested rAAV vector production with our protocol using commerciallyavailable and published plasmids. First, the plasmids from Agilent's AAVHelper-Free System were tested. Since Agilent only has pAAV-RC forrAAV2, we replaced the cap gene of AAV2 in pAAV-RC with the cap gene ofAAV8 (pAGL2/8). Both rAAV2- and rAAV8-LacZ vectors produced usingAgilent's plasmids were compared with the yields of rAAV2- andrAAV8-eGFP vectors using our in-house plasmids. The use of pAGL2/8 andpAAV2-RC yielded about 50% and 89% less rAAV2/8 and rAAV2 vectors,respectively, as compared with Amgen's plasmids (FIGS. 8A and B). Thus,the DOE-improved conditions could be used in rAAV2/8 vector productionwith reduced yield, but yield was significantly compromised for therAAV2 vector. Second, we tested two published pTrans vectors (pACG2 andpXX2) (Xiao X, Samulski R J. Production of high-titer recombinantadeno-associated virus vector in the absence of helper adenovirus. J.Virol. 72:2224-2232 (1998)). Our results showed that vector productionusing commercially available pACG2 and pXX2 only yielded 22.4% and 29.0%of rAAV2-EGFP vectors, respectively, as compared to our ownrecombinantly obtained plasmids (FIG. 8C).

7. Comparison of suspension HEK293T and HEK293-6E cells in theDOE-improved protocol. To investigate if other suspension HEK293 celllines could be used in DOE-improved protocol for rAAV2 and 2/8production, we replaced HEK293T suspension cells with HEK293-6E cellsthat stably express the Epstein-Barr virus nuclear antigen-1(HEK293-EBNA1) because it was a previously reported host cell line usedfor rAAV2 vector production (Durocher Y, Pham P L, St-Laurent G, JacobD, Cass B, Chahal P, Lau C J, Nalbantoglu J, Kamen A. Scalableserum-free production of recombinant adeno-associated virus type 2 bytransfection of 293 suspension cells. J Virol Methods. 144:32-40(2007)). The relative GCs in cell lysates from both DOE- andOFAT-optimized protocols were determined by bDNA assay. The resultsshowed that HEK293-6E cells produced much less rAAV2 and rAAV2/8 ascompared to HEK293T cells (FIG. 9A). This was further confirmed byImmnoblotting of capsid proteins as shown in FIG. 9B. The reason forthis is not clear. We have previously observed that HEK293-6E cells havelower transfection efficiency than that of HEK293T cells (Zhao H, WolfT, van der Valk M, Plewa C A, Sheng J, Lee K J. Cost effective andfacile method of rAAV production in suspension-adapted HEK293 cells.Mol. Ther. 19, Supplement 1:S257 (2011)). This could be an importantfactor responsible for lower yield of rAAV vectors in HEK293-6E cells.

8. Comparison of the DOE-improved protocol to a published OFAT-optimizedprotocol. Next, we compared a published protocol (Durocher Y, Pham P L,St-Laurent G, Jacob D, Cass B, Chahal P, Lau C J, Nalbantoglu J, KamenA. Scalable serum-free production of recombinant adeno-associated virustype 2 by transfection of HEK293 suspension cells. J Virol Methods.144:32-40 (2007)) with our DOE-improved protocol in terms of the yieldof rAAV2 and rAAV2/8 vector production in suspension cells. The detailedcomparison between the DOE-improved protocol and Durocher's method wasdescribed in Table 4 (below).

TABLE 4 Comparison Durocher's OFAT optimized method (Durocher, Y et al.,Scalable serum-free production of recombinant adeno-associated virustype 2 by transfection of 293 suspension cells. J Virol Methods. 144:32-40 (2007)) with DOE optimized method. In this experiment, HEK 293Tcells and medium were used in Durocher's method, and harvest at 72 hpost-transfection. Parameters Durocher's Described herein Cell Line HEK293F HEK 293T Medium Freestyle™ 293 Freestyle™ 293 Expression Medium,Expression Medium, 0.1% F68 2% FBS Cell density at  0.5  2.5transfection (×10⁶/mL) Total DNA (μg/mL)  1  1.5 Ratio 1:1:1 1:5:0.31(pHelper:pTrans:pCis) pHelper - Agilent As described herein pCis -Agilent pTrans - pACG2 TN1 and sodium No Yes butyrate Harvest post- 4872 transfection (hours)

To eliminate the differences that might result from use of differentcell lines in our and Durocher's protocols, 293T cells were used in bothexperiments. Also, in Durocher's method, the virus was harvested at 48hrs to achieve maximum IVP, while we typically harvest at 72 hrs and usetotal GC as an index for production. To normalize the resultinterpretation, rAAV vectors produced using both protocols wereharvested at 72 hrs to compare the yields using GC titration. Inaddition, experiments using Durocher's method were carried out with orwithout addition of TN1 and sodium butyrate, since our DOE-improvedprotocol included the addition of TN1 and sodium butyrate. The resultsshowed that Durocher's protocol yielded approximately 5% and 11% of thetotal GC produced using the DOE-improved protocol without and with theadditives, respectively (FIGS. 10A and 10B).

9. Protein hydrolysate (e.g., TN1) is critical for rAAV vectorproduction using the DOE-improved protocol. The concentrations ofadditivesTN1 and sodium butyrate were not optimized at the time of theDOE analysis to keep the number of runs at a manageable level. Instead,we employed the concentration of TN1 (0.5%) that is commonly used inrecombinant protein production and the concentration of sodium butyrate(5 mM) used in our OFAT-protocol for rAAV2/5 vector production. Toverify the effects of TN1 and sodium butyrate in rAAV2/8 vectorproduction using the DOE-improved protocol, TN1 and sodium butyrate wereremoved or added separately to the cells, and the vector production wasevaluated by quantifying capsid protein levels in lysates by Immunoblot.No capsid protein was detected in the absence of TN1, suggesting acritical role for TN1 in the newly established protocol. Addition ofsodium butyrate further increased AAV capsid protein expression (datanot shown). Therefore, a second DOE-optimization was pursued to optimizethe concentrations of TN1 and sodium butyrate with the range of TN1 from0-2% and sodium butyrate from 0-20 mM (Table 5, below).

TABLE 5 DOE-optimization to optimize the concentrations of TN1 andsodium butyrate. Experimental susp. Conditions Range of Optimal 90% ofrAAV2/5 Additives DOE concentration optimal (OFAT)^($) TN1 (% w/v)^($)0-2  1.5 1.475-1.525 0.5 Sodium 0-20 0 0-1 5 butyrate (mM)^($) ^($)Phamet al, Biotechnol Bioeng, 90: 332-344, 2005, Palermo et al., JBiotechnol. 19: 35-47, (1991) and Zhao et al. Mol. Ther. 19 Supplement1: S257 (2011).

In this experiment, the concentration of GC per liter from cell lysateswas determined by bDNA assay (FIG. 11A), and we confirmed that TN1 iscritical in rAAV2/8 vector production. The results from the experimentwere analyzed by the computer program and the prediction profile showedthat the optimal TN1 concentration is 1.5% (w/v) and that sodiumbutyrate is unnecessary for rAAV2/8 vector production (FIG. 11B). Thisnew identified optimal condition was compared with the previously usedTN1 and sodium butyrate concentrations (FIG. 11C) and we found that asimilar amount of rAAV2/8 vectors was produced under the protocols wheresodium butyrate was both absent and present, indicating that sodiumbutyrate is not necessary. However, when these optimal conditions wereapplied to large scale (1-L) of rAAV2/8-empty vector production (rAAV2/8does not carry GOI), much less rAAV vectors by 10-folds were obtained ascompared to small scale culture (20 ml) (FIG. 11D-E). In this study, 20ml of cells were also removed from 1-L culture immediately aftertransfection and cultured in a 125 ml flask to rule out any cell densityand transfection variations (20 ml from 1 L). Twenty-four hours posttransfection, different amount of TN1 and sodium butyrate were added tothe culture. rAAVs were then purified, analyzed and titrated by silverstain and bDNA assay (FIG. 11D and FIG. 11E). It is evident thatproduction with DOE optimized condition (TN1=1.5% w/v) is as efficientas the conditions before optimization (TN1=0.5% w/v, sodium butyrate=5mM) in small scale, but not in 1-L culture. The cause for this is notclear, but it could be due to culture conditions between small scale (in125-ml flask with shacking speed 110 rpm) and large scale (in 3-L flaskwith shacking speed 65 rpm. Therefore, rAAV vector production in thepresence of sodium butyrate (TN1=0.5% w/v and sodium butyrate=5 mM) wasmore optimal for large scale rAAV virion production.

Interestingly, as shown in Table 2 (above), the values identified fortwo parameters, cell density and plasmid ratios, are notably differentfrom the previously reported values identified via optimization with theOFAT method. Using the OFAT method, we and others (Zhao H, Wolf T, vander Valk M, Plewa C A, Sheng J, Lee K J. Cost effective and facilemethod of rAAV production in suspension-adapted HEK293 cells. Mol. Ther.19, Supplement 1:S257 (2011)), and Durocher Y, Pham P L, St-Laurent G,Jacob D, Cass B, Chahal P, Lau C J, Nalbantoglu J, Kamen A. Scalableserum-free production of recombinant adeno-associated virus type 2 bytransfection of 293 suspension cells. J. Virol. Methods. 144:32-40(2007)) observed that, when the DNA amount is kept constant, higher celldensity resulted in decreased yield. In contrast, the DOE approachprojected an optimal cell density of 2.45×106 cells/ml, which wasapproximately 2.5 to 5-times higher than that obtained from OFAT methodswhile a similar amount of DNA (1.5 mg/ml) was projected, suggesting thatthe interaction between parameters plays an important role in rAAV2/8vector production.

Another striking difference between the DOE-improved values andpreviously identified parameter values was the plasmid ratio. Theplasmid ratio from the DOE optimization has a very high proportion ofpTrans, as shown in Table 2 (1:5:0.31). This translates to pTrans(encoding the cap and rep genes) making up approximately 80% the totalDNA used. Vincent, et al. reported that capsid formation is therate-limiting step in rAAV vector production (Vincent, K A et al.,Analysis of recombinant adeno-associated virus packaging andrequirements for rep and cap gene products. J. Virol. 71:1897-905(1997)). In fact, 40% more rAAV particles were produced when a plasmidencoding the cap gene under control of the CMV promoter wasco-transfected (Hildinger, M et al., High-titer, serum-free productionof adeno-associated virus vectors by polyethyleneimine-mediated plasmidtransfection in mammalian suspension cells, Biotechnol. Lett. 29:1713-21(2007)). The very high proportion of pTrans revealed by DOE-optimizationcould reflect the fact that higher cap gene expression driven by thehigh concentration of pTrans plasmid overcomes the rate-limiting step inrAAV vector production. In addition, the ratio of 1:5:0.31 uses lesspHelper and pCis-GOI, especially pCis-GOI, than that used in previouslyreported protocols. The amount of pCis-GOI is approximately 4-fold lowerin absolute amount than that used in previously reported protocols(Durocher, Y et al., Scalable serum-free production of recombinantadeno-associated virus type 2 by transfection of 293 suspension cells. JVirol Methods. 144:32-40 (2007); Hildinger, M et al., High-titer,serum-free production of adeno-associated virus vectors bypolyethyleneimine-mediated plasmid transfection in mammalian suspensioncells, Biotechnol. Lett. 29:1713-21 (2007)).

We show for the first time that a proportionally large amount of pHelperand pCis-GOI is not necessary in rAAV vector production in eitheradherent or suspension cells. This seems to contrast with the resultsfrom the OFAT optimization by Durocher's group in HEK 293E cells(Durocher Y, et al., Scalable serum-free production of recombinantadeno-associated virus type 2 by transfection on 293 suspension cells,J. Virol. Methods 144:32-40 (2007)), which showed that a higher level ofpHelper is important in rAAV2 vector production in 293E cells. Foradherent cells, the plasmid ratio was also optimized using the OFATmethod in HEK 293 cells, and a higher proportion of pHelper (60%) wasfound to be optimal (Xiao X, Samulski R J. Production of high-titerrecombinant adeno-associated virus vector in the absence of helperadenovirus. J. Virol. 72:2224-2232 (1998)). The reason for thedifference between our observation and previous reports is currently notclear, but could be due to the different optimization methods employed.In addition, the lower amount of pHelper needed in the protocol willalleviate the burden of large-scale pHelper DNA purification using anionexchange chromatography which is problematic because the large size ofthe pHelper plasmid makes elution from the column difficult. Moreover,in the DOE optimized protocol, only about 5% of the standard amount ofpCis-GOI was needed. This facilitates screening large number of GOIs invivo since the amount of each GOI plasmid required can be significantlyreduced. The reduction of the required amount of both pHelper andpCis-GOI alleviates resources required for rAAV vector production.Furthermore, we showed that the DOE-improved plasmid ratio and DNAamount was successfully applied to adherent HEK 293T cells, whichresulted in significant reduction of the total amount of DNA, and theamount of pHelper and pCis-GOI. This implies that the optimized plasmidratio could be applied to rAAV production regardless of culture modes(adherent or suspension), serotype or other rAAV plasmid system.

We used suspension HEK 293T cells for the optimization of rAAV2/5 andrAAV2/8 vector production due to its higher transfection efficiency thanthat of 293-6E (Zhao, H et al., Cost effective and facile method of rAAVproduction in suspension-adapted HEK293 cells, Mol. Ther. 19, Supplement1:S257 (2011)). As shown in FIG. 9, suspension HEK293T cells produced ahigher number of rAAV vector particles by approximately 3-fold or 5-foldin rAAV2/8 and AAV2 vectors production than that of HEK293-6E cells,respectively. The higher production yield is likely due to the highertransfection efficiency (data not shown).

It was unexpected that fewer rAAV2 vectors were produced by Agilent'splasmids using DOE-improved conditions. This could be due to adifference in the pTrans plasmids in that our pTrans was obtainedthrough extensive modification and optimization upstream of the rep ORFin order to enhance AAV cap gene expression. The modification mightreduce the rep gene expression, and could facilitate both the cap geneexpression and rAAV vector production as high rep gene expression hasbeen reported to inhibit the production of rAAV vectors (Vincent, K A etal., Analysis of recombinant adeno-associated virus packaging andrequirements for rep and cap gene products. J. Virol. 71:1897-905(1997)). The fact that fewer rAAV2 vectors were produced when ourpTrans2 was replaced with published pACG2 and pXX2 while using the samepHelper and pCis-EGFP (FIG. 8A-C) implies that the configuration ofpTrans may also play a role in rAAV vector production yields.

TN1 and sodium butyrate were used throughout our optimization processbecause higher capsid protein expression was achieved by using theseadditives in our previous optimization (Zhao, H et al., Cost effectiveand facile method of rAAV production in suspension-adapted HEK293 cells,Mol. Ther. 19, Supplement 1:S257 (2011)) and it was previously reportedthat TN1 addition increased rAAV2-EGFP production by 30% (Hildinger, M.et al., High-titer, serum-free production of adeno-associated virusvectors by polyethyleneimine-mediated plasmid transfection in mammaliansuspension cells, Biotechnol. Lett. 29:1713-21 (2007)). The roles of TN1and sodium butyrate in the DOE optimized protocol were examined againand the results indicated that TN1 played a critical role in rAAV vectorproduction. In contrast, sodium butyrate was not necessary (FIG. 11A-C)although that was not the case in our OFAT-optimized protocol (data notshown). The underlying mechanism of TN1 in rAAV vector production is notclear. However, TN1 has been reported to increase both the mRNA andrecombinant protein expression levels, suggesting it might act at bothtranscriptional and translational levels (Pham, P L et al., Transientgene expression in HEK293 cells: peptone addition posttransfectionimproves recombinant protein synthesis. Biotechnol Bioeng. 90:332-44(2005)).

In an attempt to compare rAAV vector production yields of bothDOE-improved and published OFAT-optimized protocols, Durocher's protocolwas chosen for comparison due to its simplicity and similarity to ourprocedure (Durocher, Y et al., Scalable serum-free production ofrecombinant adeno-associated virus type 2 by transfection of 293suspension cells. J Virol Methods. 144:32-40 (2007)). Unexpectedly, muchlower amounts of rAAV2 and rAAV2/8 vectors were produced usingDurocher's protocol (<5%) as compared to the DOE-improved protocol. Thisimplies that optimization using the DOE method is superior to OFAT andthat pTrans plays an important role in efficient rAAV vector production.

When yields of rAAV vector production for a particular GOI are muchlower than that of average production yields, these poor yields can bedramatically increased by further decreasing the DOE-optimized amount ofpCis plasmid. FIG. 12A shows that the yields of some rAAV vectors(rAAV8-Kcnj14 and -Paqr9) can be very low as compared to other rAAVvectors produced under the same conditions. In the experiment, rAAVvectors were produced in 1-liter cultures by triple transfection usingDOE-optimized conditions as described in Example 2 above and pHelper,pTrans2/8 and pCis encoding the GOIs. After 72 hours, transfected cellsand conditioned media containing rAAV vectors were harvested and AAV capexpression was analyzed by immunoblot analysis using anti-VP antibody(Fitzgerald Industries International, Inc., Acton, Mass., cat.#10R-A114a). The amino acid sequences of the C-terminal ends of AAV VP1,VP2, and VP3 are identical; the anti-VP antibody recognizes the peptidesequence of the C-terminus (726-733) that is common for all 3 VPs. FIGS.12B and 12C show that the AAV cap expression (B) and GC (genome copies,C) of rAAV8-Kcnj14 significantly increased with the decreased amount ofpCis-Kcnj14. In the experiment, rAAV8-Kcnj14 was generated in 20-mLcultures using DOE-optimized conditions with two times serial dilutionsof pCis-Kcnj14 from 1 (DOE-optimized amount) to 256 times ( 1/256 ofDOE-optimized amount). After harvest, VPs and GCs were analyzed byimmunoblot (FIG. 12B) and CyQuant fluorescent method (FIG. 12C) afterrAAV vector purification, respectively; FIG. 12D and FIG. 12E show thatyields of rAAV8-Paqr9 and rAAV8-Kcnj14 dramatically increased using 1/32or 1/64 of the amount of DOE-optimized pCis. These two rAAVs wereproduced in 1-liter culture using DOE-optimized conditions (1) andreduced amount of pCis ( 1/32 or 1/64). The produced rAAV8 vectors werepurified with AVB-Sepharose and quantified by CyQuant fluorescentmethod.

It appears that the production yields of rAAVvectors may significantlydiffer for different pCis-GOIs, though the DOE-optimized methods areapplied to the rAAV vector production under the same conditions. Asshown in FIG. 12A, although these eight different rAAV vectors wereproduced using the DOE-improved protocol, the amount of AAV capexpression (therefore, it correlated with the yield of rAAV vectorproduction) co-transfected with some genes such as Kcnj14 Paqr9, werevery low as compared to other genes (FIG. 12A). Since GOI can beexpressed by the pCis-GOI plasmid, we speculated that the decreased rAAVvector production could be caused by the gene product of GOI. Thus, thepCis-Kcnj14 was serially diluted from 1 (amount of DOE-improvedprotocol) to 256 times for rAAV vector production in 20-mL culture, andthe AAV cap expression and rAAV GCs were monitored. FIG. 12B and FIG.12C show that, following the dilution of pCis plasmid, both AAV capprotein expression and the yield of rAAV-Kcnj14 significantly increased,which was further confirmed by large scale (1-liter) production of theserAAVs (FIG. 12D and FIG. 12E). These results show that yields ofrAAV8-Paqr9 and rAAV8-Kcnj14 were increased dramatically by using 1/32or 1/64 amounts of pCis. GOI expression is a byproduct of rAAV vectorproduction and not necessary for generating rAAV vectors. Furthermore,GOI products could affect rAAV vector production, depending on thefunction of the GOI. The results showed here indicate that, in somecases, GOI expression can be destructive for rAAV vector production.Thus, reduction of pCis plasmid and, therefore, reduction of GOIexpression can be beneficial to the yield of rAAV vector production.

What is claimed:
 1. An in vitro method of producing a recombinant AAVvirion in a mammalian host cell, wherein the mammalian host cell is aHEK 293 cell, and wherein the cell is suspended in a transfection media,comprising contacting the cell with polyethylenimine (“PEI”) and: (i) anaccessory construct, wherein said accessory construct is a plasmid(pHelper) consisting essentially of adenoviral E2, E4Orf6, and VAI RNAgenes operably linked to an origin of replication element and one ormore other regulatory sequences; (ii) an AAV helper construct, whereinsaid AAV helper construct is a plasmid (pTrans) consisting essentiallyof AAV2 rep and AAV1, AAV2, AAV5, AAV8, or AAV9 cap coding regionsoperably linked to one or more regulatory sequences; and (iii) an AAVvector construct, wherein said AAV vector construct is a plasmid (pCis)consisting essentially of AAV2 inverted terminal repeats flanking aheterologous gene of interest operably linked to one or more regulatorysequences, wherein the ratio of pHelper:pTrans:pCis is 1:5:(0.009-0.36)(weight:weight:weight), the PEI is Transfection Grade LinearPolyethylenimine Hydrochloride (MW 40,000), and the ratio of PEI:DNA isabout 3:1.
 2. The method of claim 1, wherein the HEK 293 cell issuspended at a cell density of 2.1-3.0×10⁶ cells/mL.
 3. The method ofclaim 2, wherein the HEK 293 cell is suspended at a cell density of2.2-2.7×10⁶ cells/mL.
 4. The method of claim 3, wherein the HEK 293 cellis suspended at a cell density of about 2.5×10⁶ cells/mL.
 5. The methodof claim 1, wherein the ratio of pHelper:pTrans:pCis is 1:5:(0.30-0.36)(weight:weight:weight).
 6. The method of claim 5, wherein the ratio ofpHelper:pTrans:pCis is 1:5:0.31 (weight:weight:weight).
 7. The method ofclaim 1, wherein the total amount of plasmid does not exceed 1.5 mg/L oftransfection media.
 8. An in vitro method of producing a recombinant AAVvirion in a mammalian host cell, wherein the mammalian host cell is aHEK 293 cell, and wherein the cell adheres to a solid substrate in atransfection media, comprising contacting the cell with calciumphosphate and: an accessory construct, wherein said accessory constructis a plasmid (pHelper) consisting essentially of adenoviral E2, E4Orf6,and VAI RNA genes operably linked to an origin of replication elementand one or more other regulatory sequences; (ii) an AAV helperconstruct, wherein said AAV helper construct is a plasmid (pTrans)consisting essentially of AAV2 rep and AAV1, AAV2, AAV5, AAV8, or AAV9cap coding regions operably linked to one or more regulatory sequences;and (iii) an AAV vector construct, wherein said AAV vector construct isa plasmid (pCis) consisting essentially of AAV2 inverted terminalrepeats flanking a heterologous gene of interest operably linked to oneor more regulatory sequences, wherein the ratio of pHelper:pTrans:pCisis 1:5:(0.009-0.36) (weight:weight:weight).
 9. The method of claim 8,wherein the HEK 293 cell is seeded at a cell density of 2.1-3.0×10⁶cells/mL.
 10. The method of claim 2, wherein the HEK 293 cell is seededat a cell density of 2.2-2.7×10⁶ cells/mL.
 11. The method of claim 3,wherein the HEK 293 cell is seeded at a cell density of about 2.5×10⁶cells/mL.
 12. The method of claim 1, wherein the ratio ofpHelper:pTrans:pCis is 1:5:(0.30-0.36) (weight:weight:weight).
 13. Themethod of claim 5, wherein the ratio of pHelper:pTrans:pCis is 1:5:0.31(weight:weight:weight).
 14. The method of claim 1, wherein the totalamount of plasmid does not exceed 1.5 mg/L of transfection media.